CED
Clinical dermatology • Original article
Clinical and Experimental Dermatology
Dermoscopic features in fungal melanonychia I. Kilinc Karaarslan,1 A. Acar,1 D. Aytimur,1 T. Akalin2 and F. Ozdemir1 Departments of 1Dermatology and 2Pathology, Medical Faculty, Ege University, Izmir, Turkey doi:10.1111/ced.12552
Summary
Background. Data on the dermoscopic features of fungal melanonychia are limited. Aim. To identify the dermoscopic features of fungal melanonychia. Methods. We reviewed patient files, clinical history and dermoscopic images of all cases with a diagnosis of fungal melanonychia seen at our dermoscopy unit within the past year. Results. In total, 14 cases with 20 involved nails were reviewed. The most common type of melanonychia was melanonychia striata (7/20). Multicoloured pigmentation was observed in 19 of the nails. The main dermoscopic pattern was homogeneous pigmentation; however, black pigmented aggregates, presenting as either coarse granules or pigmented clumps, accompanied this homogeneous pigmentation in 16 lesions. Matt black pigmentation, matt white pigmentation, yellow to brown pigmentation, black reverse triangle (wider at the distal than the proximal end), superficial transverse striation and blurred appearance were the other features. Conclusions. We have identified a number of dermoscopic features appearing in fungal melanonychia, which should help in diagnosis of this disease.
Introduction Pigmented lesions on the nail are common, and can be challenging for clinicians, especially in making the differential diagnosis. A pigmented and dystrophic nail should raise the suspicion of melanoma, and this should be excluded before considering other diagnoses. If there is no other indication for melanoma clinically or dermoscopically, then onychomycosis with pigmentation (fungal melanonychia; FM) should be considered. Hutchinson sign is an important clue for the diagnosis of melanoma on the nail unit, and in such cases, diagnosis of melanoma is straightforward. In cases with features such as melanonychia on the distal portion of the nail and subungual hyperkeratosis, FM is also relatively Correspondence: Dr Isil Kilinc Karaarslan, Department of Dermatology, Dermoscopy/Dermato-oncology Unit, Faculty of Medicine, University of Ege (Aegean), 35100, Bornova, Izmir, Turkey E-mail: [email protected] Conflict of interest: the authors declare that they have no conflicts of interest. Accepted for publication 11 May 2014
ª 2014 British Association of Dermatologists
easy to diagnose. However, as reported in the literature,1 if the pigmentation involves the proximal portion of the nail and there is no Hutchinson sign, differentiating between melanoma and FM may be difficult. Dermoscopy, a valid in vivo technique, has great potential, especially in the diagnosis of pigmented skin lesions. Although there is well-established information in the literature regarding the dermoscopic features of melanoma in the nail unit, data on the dermoscopic features of FM are limited. Homogeneous pigmentation (brown, grey or black), which presents as pigmented lines or structureless discolouration, and absence of visible melanin inclusions (namely, tiny granules, which are < 0.1 mm in size) are the reported dermoscopic features of FM.2–4 Additionally, the dermoscopic features of onychomycosis have recently been studied in a series that did not include any case of FM. Irregular matt pigmentation (white, or yellow to brown) seen as linear or homogeneous pigmented areas and a jagged edge (proximal margin of the onycholytic area) were the dermoscopic features of onychomycosis observed in that report.5
Clinical and Experimental Dermatology
1
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(c)
(b)
(e)
(d)
Figure 1 Types of fungal melanonychia: (a) melanonychia striata, (b) distal partial diffuse type, (c) proximal partial diffuse type,
(d) distal linear type and (e) total diffuse type.
Because of this paucity of data on FM in the literature, and because we have treated some difficult cases of FM at our centre, we reviewed all cases of FM seen during the course of 1 year to try to identify additional dermoscopic features of FM that might be useful in aiding diagnosis.
total) to obtain samples for the identification of any pigmented lesion. Direct fungal examination and fungal culture were performed in all cases. Direct examination of the nail samples with 20% potassium hydroxide (KOH) was performed, and the samples were cultured on Sabouraud glucose agar with and without cyclohexamide at 27 °C.
Methods We reviewed the patient files and the clinical and dermoscopic images of the cases with the diagnosis of FM seen at our dermoscopy unit within 1 year. Dermoscopy (dermatoscopy, epiluminescence microscopy) is a non-invasive diagnostic technique for the in vivo observation of pigmented skin lesions. Dermoscopic examination was performed by using a hand-held dermoscope which had a 10-fold magnification (Dermlite DL3, 3GEN, USA). Dermoscopic images were taken with a digital camera connected to the dermoscope. As melanonychia describes brown–black pigmentation of the nail plate,6 we excluded lesions diagnosed as onychomycosis showing diffuse light yellow– brown pigmentation. Any lesions with pigmentation of a greenish hue accompanying the brown–black pigmentation were also excluded, as these raised the possibility of complication with Pseudomonas infection. We carried out curettage (removal of the entire pigmented portion of the nail) or nail avulsion (partial or
2
Clinical and Experimental Dermatology
Results We reviewed 14 patients (10 men, 4 women; mean SD; age 42 age 3.2 years, range 18–80). One patient was aged under 30 years, 3 were aged over 65 years, and the remaining 10 patients fell between these ages. Between the 14 patients, there were 20 diseased nails; 10 patients had only 1 involved nail, 3 patients had 2 involved nails, and 1 patient had 4 involved nails. The duration of the pigmentation ranged from 8 months to 10 years; in 7 patients it was < 1 year, in 4 patients it was > 5 years and in the remaining 3 patients, it ranged from 1 to 5 years. Of the 14 patients, 7 (50%) had an accompanying systemic illness (1 of these patients had 2 illnesses): 4 had a history of malignancy (with 2 of these having a previous diagnosis of cutaneous melanoma), 2 had diabetes mellitus and 2 were receiving immunosuppressive treatment.
ª 2014 British Association of Dermatologists
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Figure 2 (a–h) Dermoscopy images showing (a–g) multicoloured pigmentation, (h) pure grey–black pigmentation.
Morphologically, 19 of the nails had yellow, brown, grey, black or multicoloured pigmentation. Only one lesion had grey–black pigmentation alone. The most common type of melanonychia was melanonychia striata (7/20), presenting as a pigmented band extending longitudinally from the proximal nail fold or the lunula to the free edge of the nail plate. The other types of melanonychia were distal partial diffuse type (5/20), proximal partial diffuse
ª 2014 British Association of Dermatologists
type (4/20), distal linear type (2/20), and total diffuse type (2/20) (Fig. 1). Using dermoscopy, we found multicoloured pigmentation (yellow, brown, grey and/or black. and in some cases, also red due to haemorrhage) was seen in 19 lesions, and pure grey-black pigmentation in 1 lesion (Fig. 2a–h). The main pattern of pigmentation was homogeneous; however, black pigment aggregates accompanied the homogeneous pigmentation in 16
Clinical and Experimental Dermatology
3
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(b)
Figure 3 (a) Homogeneous pigmentation without any pigment aggregates. (b) Black pigment aggregates accompanying homogeneous
pigmentation. Coarse granules (white circles) and pigmented clumps (red circles) are visible.
(a)
(b)
(c)
(d)
Figure 4 Irregular matt white, yellow or brown pigmentation seen as (a) pigmented areas or (b) longitudinal pigmentation. Irregular
matt black pigmentation seen as (c) pigmented areas or (d) longitudinal pigmentation.
lesions, while in the remaining 4 lesions, these black pigment aggregates were not seen (Fig. 3a). Pigment aggregates were visible, which were considered to be either coarse granules (matt black, roundish structures > 0.1 mm in size or pigmented clumps (aggregated multiple coarse granules that formed larger, irregular shaped structures) (Fig. 3b). Several other dermoscopic features were observed. Irregular matt white, yellow or brown pigmentation (19/20) was seen as either pigmented areas (14/20) or longitudinal pigmentation (10/20). The black pigmented version, termed irregular matt black pigmentation (19/20) was seen as pigmented areas (10/20) or
4
Clinical and Experimental Dermatology
longitudinal pigmentation (9/20) (Fig. 4). In five lesions, this longitudinal pigmentation was disrupted, given the appearance of a dashed line. Red homogeneous pigmentation (due to haemorrhage) (12/20), blurred appearance (9/20), superficial transverse striation (7/20), jagged edges (3/20) and black reverse triangle (pigmentation that was wider at the distal than the proximal end; 2/20) were also seen (Fig. 5). Hutchinson sign was negative in all cases, but two lesions were positive for pseudo-Hutchinson sign. These lesions were difficult to differentiate from a melanocytic lesion (Fig. 6). One of these patients (lesion 9) had been receiving topical antifungal
ª 2014 British Association of Dermatologists
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(b)
(c)
(d)
Figure 5 (a) Superficial transverse striation, (b) jagged edge, (c,d) black reverse triangle.
(a)
(b)
(c)
(d)
Figure 6 (a,c) Two cases of fungal melanonychia that were difficult to differentiate from a melanocytic lesion (dermoscopic images of
these lesions are shown as insets). (b,d) Examination of the nail bed of these lesions for the existence of any pigmented lesion by partial or total nail avulsion was performed.
treatment, but otherwise none of the cases had received topical or systemic antifungal treatment within the previous 3 months. No pigment was observed on the nail bed after curettage or nail avulsion in any of the cases.
ª 2014 British Association of Dermatologists
Direct microscopic examination of the nail samples in a KOH preparation was positive for 19 lesions (95%), and the remaining lesion with a negative result had a positive fungal culture. Fungal elements with a diffuse yellow–brown to green pigmentation in the
Clinical and Experimental Dermatology
5
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(b)
(c)
(d)
Figure 7 (a,b) Fungal elements on a diffuse yellow–brown to green pigmented background, and brown–black amorphous pigment deposits (arrows) on direct microscopic examination of the nail samples in a potassium hydroxide preparation (original magnification 9 400). (c) Yellow–brown diffuse pigmentation in the background, accompanying the fungal structures (hyphae or spores) and (d) hyperkeratotic nodules containing numerous clumped hyphae (dermatophytoma) on histopathological sample. Periodic-acid–Schiff, original magnification (c) 9 200; (d) 9 40, (inset)9 400.
background were found in all samples. Various amounts of brown–black amorphous pigment deposits were seen, and in some preparations, pigmented hyphae were also observed (Fig. 7a,b). Trichophyton rubrum was the most common agent detected in fungal cultures (18 lesions, 90%), and Candida albicans was detected in one lesion. In lesion 9, direct microscopic examination was positive but fungal culture was negative (probably due to the topical antifungal treatment the patient was using). Five lesions were examined histopathologically. In each lesion, a yellow–brown diffuse pigmentation on the background accompanying the fungal structures (hyphae or spores) within the nail plate was seen. The pigmentation was widespread in some cases and focal in some others. Hyperkeratotic nodules containing
6
Clinical and Experimental Dermatology
numerous clumped hyphae (dermatophytoma) were also observed in some lesions (Fig. 7c,d). Masson– Fontana staining was negative in all lesions.
Discussion FM is a dark pigmentation of the nails caused by fungal infection,6 and is a rare nail disorder. In such cases, melanoma should be excluded from the differential diagnosis. In the nail unit, melanocytes are found both in the nail matrix and the nail bed epithelium; those in the former location produce melanin, but those in the latter do not. Consequently, melanomas originating from the nail bed tend to be amelanotic.7 Thus, when dealing with melanonychia originating from the proximal nail unit, especially in cases
ª 2014 British Association of Dermatologists
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
Figure 8 Chart for the differential diagnosis of a pigmented dystrophic nail.
without Hutchinson sign, the possibility of a melanocytic lesion should be considered, and it is essential to ensure that it is not melanoma. In their review article on the diagnosis and management of nail pigmentations, Braun et al.2 suggested that in nonmelanocytic lesions such as fungal infections, the pigment tends to be distributed homogeneously. They emphasized that melanin is found in cellular inclusions, and can be easily identified in melanocytic lesions as tiny granules < 0.1 mm in diameter under dermoscopy. Braun et al. presented a case of FM caused by T. rubrum, and reported that homogeneous pigmentation devoid of visible melanin inclusions helped to identify the pigmentation correctly as being of nonmelanocytic origin.2 In their study evaluating the dermoscopic and histopathological features of 10 cases of longitudinal melanoncyhia, Hirata et al.3 also reported a case of FM, and described it as having a brown background with black regular lines under dermoscopy. Piraccini et al.5 described the dermoscopic features of distal subungual onychomycosis, not including FM. The features they reported as specific to this disease included jagged edge (sharp longitudinal whitish indentations directed to the proximal nail fold) and irregular matt pigmentation (white to yellow, orange or brown in colour) distributed in longitudinal striae. Blackish dots and globules (due to subungual haemor-
ª 2014 British Association of Dermatologists
rhages) were also observed. Piraccini et al. concluded that the jagged edge resulted from the proximal progression of dermatophytes through the horny layer of the nail bed, along the longitudinal ridges, and that the matt discolouration reflected the colour of the colonies, scales and subungual debris. Yellow–orange homogeneous matt colour was reported to characterize dermathophytoma.5 In our study, multicoloured pigmentation (yellow, brown, grey, black or red), matt black pigmentation (seen as lines, disrupted black linear pigmentation or homogeneous areas), black pigment aggregates (seen as coarse granules and/or pigment clumps), black reverse triangle, superficial transverse striation and blurred appearance were the additional dermoscopic features wer found in FM. The coarse granules and pigment clumps, which we found to be the important dermoscopic features for differentiating FM from other conditions, correlated well with the accumulation of fungal colonies and the pigment produced by the fungi, seen in histopathological samples. The major limitations of this study are the small sample size and the lack of blinded evaluation of the images. However, we consider that the dermoscopic features observed in this study may aid in the differential diagnosis of the pigmented lesions seen on nails. The diagram shown in Fig. 8 may guide the physician in the diagnosis of FM using these features.
Clinical and Experimental Dermatology
7
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
Conclusion We reviewed 14 patients with 20 lesions diagnosed as FM, and identified a number of dermoscopic features, which should aid in the clinical diagnosis of this condition.
What’s already known about this topic? • There are few reports in the literature about
the diagnostic features of FM. • Homogeneous pigmentation is one of the
dermoscopic features of fungal melanonychia.
What does this study add? • Multicoloured, matt black, matt white, or yel-
low to brown pigmentation, black pigment aggregates (coarse granules and/or pigment clumps), black reverse triangle, superficial transverse striation and blurred appearance of pigmentation under dermoscopy are features of FM that can help in the differential diagnosis of this condition.
8
Clinical and Experimental Dermatology
References 1 Blum A. Onychomycosis with onychodystrophy or acrolentiginous melanoma with onychomycosis and onychodystrophy? Hautarzt 2012; 63: 341–3. 2 Braun RP, Baran R, Le Gal FA et al. Diagnosis and management of nail pigmentations. J Am Acad Dermatol 2007; 56: 835–47. 3 Hirata SH, Yamada S, Almeida FA et al. Dermoscopic examination of the nail bed and matrix. Int J Dermatol 2006; 45: 28–30. 4 Kittler H, Rosendahl C, Cameron A et al. Dermatoscopy of Nail Pigmentation. In: Dermatoscopy. An Algorithmic Method Based on Pattern Analysis, 1st edn (Kittler H, Rosendahl C, Cameron A, Tschandl P, eds). Vienna: Facultas, 2011; 212–15. 5 Piraccini BM, Balestri R, Starace M et al. Nail digital dermoscopy (onychoscopy) in the diagnosis of onychomycosis. J Eur Acad Dermatol Venereol 2013; 27: 509–13. 6 Finch J, Arenas R, Baran R. Fungal melanonychia. J Am Acad Dermatol 2012; 66: 830–41. 7 Ruben BS. Pigmented lesions of the nail unit: clinical and histopathologic features. Semin Cutan Med Surg 2010; 29: 148–58.
ª 2014 British Association of Dermatologists
Clinical dermatology • Original article
Clinical and Experimental Dermatology
Dermoscopic features in fungal melanonychia I. Kilinc Karaarslan,1 A. Acar,1 D. Aytimur,1 T. Akalin2 and F. Ozdemir1 Departments of 1Dermatology and 2Pathology, Medical Faculty, Ege University, Izmir, Turkey doi:10.1111/ced.12552
Summary
Background. Data on the dermoscopic features of fungal melanonychia are limited. Aim. To identify the dermoscopic features of fungal melanonychia. Methods. We reviewed patient files, clinical history and dermoscopic images of all cases with a diagnosis of fungal melanonychia seen at our dermoscopy unit within the past year. Results. In total, 14 cases with 20 involved nails were reviewed. The most common type of melanonychia was melanonychia striata (7/20). Multicoloured pigmentation was observed in 19 of the nails. The main dermoscopic pattern was homogeneous pigmentation; however, black pigmented aggregates, presenting as either coarse granules or pigmented clumps, accompanied this homogeneous pigmentation in 16 lesions. Matt black pigmentation, matt white pigmentation, yellow to brown pigmentation, black reverse triangle (wider at the distal than the proximal end), superficial transverse striation and blurred appearance were the other features. Conclusions. We have identified a number of dermoscopic features appearing in fungal melanonychia, which should help in diagnosis of this disease.
Introduction Pigmented lesions on the nail are common, and can be challenging for clinicians, especially in making the differential diagnosis. A pigmented and dystrophic nail should raise the suspicion of melanoma, and this should be excluded before considering other diagnoses. If there is no other indication for melanoma clinically or dermoscopically, then onychomycosis with pigmentation (fungal melanonychia; FM) should be considered. Hutchinson sign is an important clue for the diagnosis of melanoma on the nail unit, and in such cases, diagnosis of melanoma is straightforward. In cases with features such as melanonychia on the distal portion of the nail and subungual hyperkeratosis, FM is also relatively Correspondence: Dr Isil Kilinc Karaarslan, Department of Dermatology, Dermoscopy/Dermato-oncology Unit, Faculty of Medicine, University of Ege (Aegean), 35100, Bornova, Izmir, Turkey E-mail: [email protected] Conflict of interest: the authors declare that they have no conflicts of interest. Accepted for publication 11 May 2014
ª 2014 British Association of Dermatologists
easy to diagnose. However, as reported in the literature,1 if the pigmentation involves the proximal portion of the nail and there is no Hutchinson sign, differentiating between melanoma and FM may be difficult. Dermoscopy, a valid in vivo technique, has great potential, especially in the diagnosis of pigmented skin lesions. Although there is well-established information in the literature regarding the dermoscopic features of melanoma in the nail unit, data on the dermoscopic features of FM are limited. Homogeneous pigmentation (brown, grey or black), which presents as pigmented lines or structureless discolouration, and absence of visible melanin inclusions (namely, tiny granules, which are < 0.1 mm in size) are the reported dermoscopic features of FM.2–4 Additionally, the dermoscopic features of onychomycosis have recently been studied in a series that did not include any case of FM. Irregular matt pigmentation (white, or yellow to brown) seen as linear or homogeneous pigmented areas and a jagged edge (proximal margin of the onycholytic area) were the dermoscopic features of onychomycosis observed in that report.5
Clinical and Experimental Dermatology
1
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(c)
(b)
(e)
(d)
Figure 1 Types of fungal melanonychia: (a) melanonychia striata, (b) distal partial diffuse type, (c) proximal partial diffuse type,
(d) distal linear type and (e) total diffuse type.
Because of this paucity of data on FM in the literature, and because we have treated some difficult cases of FM at our centre, we reviewed all cases of FM seen during the course of 1 year to try to identify additional dermoscopic features of FM that might be useful in aiding diagnosis.
total) to obtain samples for the identification of any pigmented lesion. Direct fungal examination and fungal culture were performed in all cases. Direct examination of the nail samples with 20% potassium hydroxide (KOH) was performed, and the samples were cultured on Sabouraud glucose agar with and without cyclohexamide at 27 °C.
Methods We reviewed the patient files and the clinical and dermoscopic images of the cases with the diagnosis of FM seen at our dermoscopy unit within 1 year. Dermoscopy (dermatoscopy, epiluminescence microscopy) is a non-invasive diagnostic technique for the in vivo observation of pigmented skin lesions. Dermoscopic examination was performed by using a hand-held dermoscope which had a 10-fold magnification (Dermlite DL3, 3GEN, USA). Dermoscopic images were taken with a digital camera connected to the dermoscope. As melanonychia describes brown–black pigmentation of the nail plate,6 we excluded lesions diagnosed as onychomycosis showing diffuse light yellow– brown pigmentation. Any lesions with pigmentation of a greenish hue accompanying the brown–black pigmentation were also excluded, as these raised the possibility of complication with Pseudomonas infection. We carried out curettage (removal of the entire pigmented portion of the nail) or nail avulsion (partial or
2
Clinical and Experimental Dermatology
Results We reviewed 14 patients (10 men, 4 women; mean SD; age 42 age 3.2 years, range 18–80). One patient was aged under 30 years, 3 were aged over 65 years, and the remaining 10 patients fell between these ages. Between the 14 patients, there were 20 diseased nails; 10 patients had only 1 involved nail, 3 patients had 2 involved nails, and 1 patient had 4 involved nails. The duration of the pigmentation ranged from 8 months to 10 years; in 7 patients it was < 1 year, in 4 patients it was > 5 years and in the remaining 3 patients, it ranged from 1 to 5 years. Of the 14 patients, 7 (50%) had an accompanying systemic illness (1 of these patients had 2 illnesses): 4 had a history of malignancy (with 2 of these having a previous diagnosis of cutaneous melanoma), 2 had diabetes mellitus and 2 were receiving immunosuppressive treatment.
ª 2014 British Association of Dermatologists
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Figure 2 (a–h) Dermoscopy images showing (a–g) multicoloured pigmentation, (h) pure grey–black pigmentation.
Morphologically, 19 of the nails had yellow, brown, grey, black or multicoloured pigmentation. Only one lesion had grey–black pigmentation alone. The most common type of melanonychia was melanonychia striata (7/20), presenting as a pigmented band extending longitudinally from the proximal nail fold or the lunula to the free edge of the nail plate. The other types of melanonychia were distal partial diffuse type (5/20), proximal partial diffuse
ª 2014 British Association of Dermatologists
type (4/20), distal linear type (2/20), and total diffuse type (2/20) (Fig. 1). Using dermoscopy, we found multicoloured pigmentation (yellow, brown, grey and/or black. and in some cases, also red due to haemorrhage) was seen in 19 lesions, and pure grey-black pigmentation in 1 lesion (Fig. 2a–h). The main pattern of pigmentation was homogeneous; however, black pigment aggregates accompanied the homogeneous pigmentation in 16
Clinical and Experimental Dermatology
3
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(b)
Figure 3 (a) Homogeneous pigmentation without any pigment aggregates. (b) Black pigment aggregates accompanying homogeneous
pigmentation. Coarse granules (white circles) and pigmented clumps (red circles) are visible.
(a)
(b)
(c)
(d)
Figure 4 Irregular matt white, yellow or brown pigmentation seen as (a) pigmented areas or (b) longitudinal pigmentation. Irregular
matt black pigmentation seen as (c) pigmented areas or (d) longitudinal pigmentation.
lesions, while in the remaining 4 lesions, these black pigment aggregates were not seen (Fig. 3a). Pigment aggregates were visible, which were considered to be either coarse granules (matt black, roundish structures > 0.1 mm in size or pigmented clumps (aggregated multiple coarse granules that formed larger, irregular shaped structures) (Fig. 3b). Several other dermoscopic features were observed. Irregular matt white, yellow or brown pigmentation (19/20) was seen as either pigmented areas (14/20) or longitudinal pigmentation (10/20). The black pigmented version, termed irregular matt black pigmentation (19/20) was seen as pigmented areas (10/20) or
4
Clinical and Experimental Dermatology
longitudinal pigmentation (9/20) (Fig. 4). In five lesions, this longitudinal pigmentation was disrupted, given the appearance of a dashed line. Red homogeneous pigmentation (due to haemorrhage) (12/20), blurred appearance (9/20), superficial transverse striation (7/20), jagged edges (3/20) and black reverse triangle (pigmentation that was wider at the distal than the proximal end; 2/20) were also seen (Fig. 5). Hutchinson sign was negative in all cases, but two lesions were positive for pseudo-Hutchinson sign. These lesions were difficult to differentiate from a melanocytic lesion (Fig. 6). One of these patients (lesion 9) had been receiving topical antifungal
ª 2014 British Association of Dermatologists
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(b)
(c)
(d)
Figure 5 (a) Superficial transverse striation, (b) jagged edge, (c,d) black reverse triangle.
(a)
(b)
(c)
(d)
Figure 6 (a,c) Two cases of fungal melanonychia that were difficult to differentiate from a melanocytic lesion (dermoscopic images of
these lesions are shown as insets). (b,d) Examination of the nail bed of these lesions for the existence of any pigmented lesion by partial or total nail avulsion was performed.
treatment, but otherwise none of the cases had received topical or systemic antifungal treatment within the previous 3 months. No pigment was observed on the nail bed after curettage or nail avulsion in any of the cases.
ª 2014 British Association of Dermatologists
Direct microscopic examination of the nail samples in a KOH preparation was positive for 19 lesions (95%), and the remaining lesion with a negative result had a positive fungal culture. Fungal elements with a diffuse yellow–brown to green pigmentation in the
Clinical and Experimental Dermatology
5
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
(a)
(b)
(c)
(d)
Figure 7 (a,b) Fungal elements on a diffuse yellow–brown to green pigmented background, and brown–black amorphous pigment deposits (arrows) on direct microscopic examination of the nail samples in a potassium hydroxide preparation (original magnification 9 400). (c) Yellow–brown diffuse pigmentation in the background, accompanying the fungal structures (hyphae or spores) and (d) hyperkeratotic nodules containing numerous clumped hyphae (dermatophytoma) on histopathological sample. Periodic-acid–Schiff, original magnification (c) 9 200; (d) 9 40, (inset)9 400.
background were found in all samples. Various amounts of brown–black amorphous pigment deposits were seen, and in some preparations, pigmented hyphae were also observed (Fig. 7a,b). Trichophyton rubrum was the most common agent detected in fungal cultures (18 lesions, 90%), and Candida albicans was detected in one lesion. In lesion 9, direct microscopic examination was positive but fungal culture was negative (probably due to the topical antifungal treatment the patient was using). Five lesions were examined histopathologically. In each lesion, a yellow–brown diffuse pigmentation on the background accompanying the fungal structures (hyphae or spores) within the nail plate was seen. The pigmentation was widespread in some cases and focal in some others. Hyperkeratotic nodules containing
6
Clinical and Experimental Dermatology
numerous clumped hyphae (dermatophytoma) were also observed in some lesions (Fig. 7c,d). Masson– Fontana staining was negative in all lesions.
Discussion FM is a dark pigmentation of the nails caused by fungal infection,6 and is a rare nail disorder. In such cases, melanoma should be excluded from the differential diagnosis. In the nail unit, melanocytes are found both in the nail matrix and the nail bed epithelium; those in the former location produce melanin, but those in the latter do not. Consequently, melanomas originating from the nail bed tend to be amelanotic.7 Thus, when dealing with melanonychia originating from the proximal nail unit, especially in cases
ª 2014 British Association of Dermatologists
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
Figure 8 Chart for the differential diagnosis of a pigmented dystrophic nail.
without Hutchinson sign, the possibility of a melanocytic lesion should be considered, and it is essential to ensure that it is not melanoma. In their review article on the diagnosis and management of nail pigmentations, Braun et al.2 suggested that in nonmelanocytic lesions such as fungal infections, the pigment tends to be distributed homogeneously. They emphasized that melanin is found in cellular inclusions, and can be easily identified in melanocytic lesions as tiny granules < 0.1 mm in diameter under dermoscopy. Braun et al. presented a case of FM caused by T. rubrum, and reported that homogeneous pigmentation devoid of visible melanin inclusions helped to identify the pigmentation correctly as being of nonmelanocytic origin.2 In their study evaluating the dermoscopic and histopathological features of 10 cases of longitudinal melanoncyhia, Hirata et al.3 also reported a case of FM, and described it as having a brown background with black regular lines under dermoscopy. Piraccini et al.5 described the dermoscopic features of distal subungual onychomycosis, not including FM. The features they reported as specific to this disease included jagged edge (sharp longitudinal whitish indentations directed to the proximal nail fold) and irregular matt pigmentation (white to yellow, orange or brown in colour) distributed in longitudinal striae. Blackish dots and globules (due to subungual haemor-
ª 2014 British Association of Dermatologists
rhages) were also observed. Piraccini et al. concluded that the jagged edge resulted from the proximal progression of dermatophytes through the horny layer of the nail bed, along the longitudinal ridges, and that the matt discolouration reflected the colour of the colonies, scales and subungual debris. Yellow–orange homogeneous matt colour was reported to characterize dermathophytoma.5 In our study, multicoloured pigmentation (yellow, brown, grey, black or red), matt black pigmentation (seen as lines, disrupted black linear pigmentation or homogeneous areas), black pigment aggregates (seen as coarse granules and/or pigment clumps), black reverse triangle, superficial transverse striation and blurred appearance were the additional dermoscopic features wer found in FM. The coarse granules and pigment clumps, which we found to be the important dermoscopic features for differentiating FM from other conditions, correlated well with the accumulation of fungal colonies and the pigment produced by the fungi, seen in histopathological samples. The major limitations of this study are the small sample size and the lack of blinded evaluation of the images. However, we consider that the dermoscopic features observed in this study may aid in the differential diagnosis of the pigmented lesions seen on nails. The diagram shown in Fig. 8 may guide the physician in the diagnosis of FM using these features.
Clinical and Experimental Dermatology
7
Dermoscopy of fungal melanonychia K. I. Kilinc et al.
Conclusion We reviewed 14 patients with 20 lesions diagnosed as FM, and identified a number of dermoscopic features, which should aid in the clinical diagnosis of this condition.
What’s already known about this topic? • There are few reports in the literature about
the diagnostic features of FM. • Homogeneous pigmentation is one of the
dermoscopic features of fungal melanonychia.
What does this study add? • Multicoloured, matt black, matt white, or yel-
low to brown pigmentation, black pigment aggregates (coarse granules and/or pigment clumps), black reverse triangle, superficial transverse striation and blurred appearance of pigmentation under dermoscopy are features of FM that can help in the differential diagnosis of this condition.
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Clinical and Experimental Dermatology
References 1 Blum A. Onychomycosis with onychodystrophy or acrolentiginous melanoma with onychomycosis and onychodystrophy? Hautarzt 2012; 63: 341–3. 2 Braun RP, Baran R, Le Gal FA et al. Diagnosis and management of nail pigmentations. J Am Acad Dermatol 2007; 56: 835–47. 3 Hirata SH, Yamada S, Almeida FA et al. Dermoscopic examination of the nail bed and matrix. Int J Dermatol 2006; 45: 28–30. 4 Kittler H, Rosendahl C, Cameron A et al. Dermatoscopy of Nail Pigmentation. In: Dermatoscopy. An Algorithmic Method Based on Pattern Analysis, 1st edn (Kittler H, Rosendahl C, Cameron A, Tschandl P, eds). Vienna: Facultas, 2011; 212–15. 5 Piraccini BM, Balestri R, Starace M et al. Nail digital dermoscopy (onychoscopy) in the diagnosis of onychomycosis. J Eur Acad Dermatol Venereol 2013; 27: 509–13. 6 Finch J, Arenas R, Baran R. Fungal melanonychia. J Am Acad Dermatol 2012; 66: 830–41. 7 Ruben BS. Pigmented lesions of the nail unit: clinical and histopathologic features. Semin Cutan Med Surg 2010; 29: 148–58.
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