Clinical and Experimental Dermatology (1977) 2, 265.
An unusual congenital nail dystrophy ('soft nail disease')
GIORGIO PRANDI AND MASSIMO CACCIALANZA Clinica Dermatologica, Universita^ di Milano, Via Pace 9, 20122 - Milanoj Italy
Accepted for publication 17 February 1977
Summary An unusual, congenital, non-familial anomaly of all finger and toe nails was observed in a 33-year-old woman. The presence of an atrophic nail plate, which was very soft, has led us to call this condition *soft nail disease'. Histological and histochemical investigations have shown this to be an anatomical and functional defect of the nail matrix which is of unknown origin.
We have recently studied a patient exhibiting an unusual congenital anomaly of the finger and toe nails. All the patient's nails were thin and soft with a short atrophic nail plate and an absent lunula. The plate had no free margin and ended abruptly without a point of separation from the nail bed. This defect, which we have tentatively called 'soft nail disease', should be regarded as an anomalous development of nails. Histological and histochemical investigations have provided some pathogenic clues, allowing some speculations on the anatomical and physiological characteristics of normal nails.
Case Report In June, 1976, a 33-year-oid housewife asked to be treated for a virus wart on her right hand. On examination, it was noted that all her finger and toe nails were abnormal (Fig. i). The nail plate was normally curved and shiny, but was thin and soft. Its antero-posterior diameter W2S shorter than usual. The lunula was absent and the nail plate ended abruptly without any point of separation. The rate of growth of the nail plate could not be determined since the patient's nails had never needed cutting. This pathological condition was responsible for an excessive sensitivity 265
Figure i. App;.arance of the finger nails.
.\.» Figure 2. Longitudinal nail section at the border between intermediate and distal hyponychium showing the abnormal peeling off of the atrophic nail plate (H & E, x ioo).
Unusual congenital nail dystrophy
267
Figure 3. High pov/er view of the nail plate showing the presence of the lower acidophilic layer and the upper basophilic parakeratotic layer (H&E, x 400).
of the distal end of the fingers and the patient had trouble in handling small objects. The defect had been present since birth but was not present in other members of the family. Hair distribution, teeth and sweating appeared to be normal. Physical examination, including radiographs of the skull, elbows, hands, back bone, pelvis and knees showed no
268
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abnormality. The EEG was normal. The caryogram revealed no chromosomal abnormalities. Rheography of the limbs was within normal limits. Mycology of affected nails was negative. A nail biopsy was carried out, according to the method of Zaias (1967). The biopsy fragment was fixed in Bouin's fiuid, embedded in paraffin and easily cut, due to its softness. Sections were stained with hematoxylin-eosin (H & E), periodic acid Schiflf (PAS) and silver impregnation, according to Gomori's method. All the portions of the hyponychium (proximal, intermediate and distal) exhibited a well evident granular layer. The nail plate was atrophic and at the border between the intermediate and distal hyponychium, the nail plate tended to peel off (Fig. 2). Serial sections showed the nail plate to be thin and consisted of two layers: a ventral, thinner, acidophilic layer surmounted by an upper, basophilic parakeratotic layer (Fig. 3). The PAS stain revealed the ventral, thinner one to be PAS positive, and the upper basophilic parakeratotic layer to be PAS negative. Finally, the existence of these two layers was confirmed by the Gomori method, the ventral, thinner layer showing significant argentophilia. Discussion This patient's anomaly ofall nails appeared to be congenital but did not affect other members of the family. It was characterized by atrophy and partial absence of the nail plate, and by total absence of the lunula. We have suggested the term 'soft nail disease' because the nail plate was as soft as normal skin. We have found no reports of a similar anomaly in previous literature (Sertoli, 1956; Pardo-Castello & Pardo-Osvaldo, i960; Samman, 1972; Zaias, 1975). 'Soft nail disease' does not appear to be associated with growth defects and in our opinion should be distinguished from familial onychatrophy which is transmitted to females only (Pires de Lima, 1924); chondro-ectodermal dysplasia (Weiss & Crosett, 1955), brachyonychia (Basset, 1962), congenital dyskeratosis (Milgrom, Stoll& Crissey, 1964), nail-patella syndrome (Silverman, Goodman & Cuppage, 1967); idiopathic nail atrophy (Samman, 1969), hidrotic and anliidrotic ectodermal defects (Rook, 1972); familial pigmentation with nail atrophy (Zaias, 1975). Aetiologically, the dystrophy may result from damage to the 'organizer region'., which controls development of the hyponychium in the embryo. The primary 'organizer', a group of actively proliferating epithelial cells forming a small groove in the proximal portion of the dorsal region of the nail phalanx, is already recognizable toward the middle of the second month of embryonic life (Sertoli, 1974). Damage to this region occurring during the first 6 weeks of pregnancy might, therefore, account for the nail changes observed here. Absence cf the lunula has prompted us to speculate on the possible interpretation of this finding. Pinkus (1927) distinguished three zones in the nail bed: the fertile terminal, the sterile medium and the fertile proximal matrix. They correspond to the distal, intermediate and proximal hyponychium (Sertoli, 1974). Proximal and intermediate hyponchium normally lack the granular layer, which in our patient was preserved. This finding also partially supports the hypothesis of Lewin (1965) who suggested that the white colour of the lunula might be due not only to a loosening of the underlying dermis, but also to an incomplete keratinization of
Unusual congenital nail dystrophy
269
the nail plate. However, our findings appear to contradict both the views of Sertoli (1974) that the colour of the lunula depends upon the presence of keratohyaline granules in the matrix, as well as that of Zaias (1975), who suggested that the colour of the lunula was due to an increased thickness of the matrix itself. The absence of the dorsal layer of the nail plate, which peeled off at the medium third of the hyponychium, indicates a physiological role of this layer in the genesis of the normal nail plate. In agreement with the data reported by Lewis (1954), Achten (1963) and Hashimoto (1971)^ the nail bed generates the ventral portion of the nail plate, which in our patient was represented by a thin horny, acidophilic, PAS positive layer. The overlying layer, in our patient, was largely parakeratotic and peeled off at the medium third of the hyponychium. We believe that this unusual nail dystrophy arises from the absence of the dorsal superficial layer, usually present in the normal nail plate, which controls the compactness of the plate itself.
References ACHTEN, G . (1963) L'ongle normal et pathologique. Dermatologica, 126, 229-245. BASSET, M . R . H . (1962) Trois formes genotypiques d'ongles courts: le pouce en raquette,
le doigts en raquette, les ongles courts simples. Bulletin de la Societe franpaise de Dermatologie et de Syphilographie, 69, 15-20. HASHIMOTO, K . (1971) Ultrastructure of human toe nail. Archiv fiir Dermatologische Eorschung, 240, 1-22.
LEWIN, K . (1965) The normal finger nail. British Journal of Dermatology, 77, 421-430. LEWIS, B.L. (1954) Microscopic studies of foetal and mature nail and surrounding soft tissue.
Archives of Dermatology, 70, 732-747. MILGROM, H . , STOLL, H.L.JR & CRISSEY, J . T . (1964) Dyscheratosis congenita. Archives of Dermatology, 89, 345-349. PARDO-CASTELLO, V. & PARDO-OSVALDO, A. (i960) Diseases of the nails (Ed. by V. Pardo-Castello and A. Pardo-Osvaldo), 3rd edn, pp. 220-233. Charles C. Thomas, Springfield, Illinois. PINKUS, F . (1927) Der Nagel. In; Handbuch der Haut und Geschlechtskrakeiten (Ed. by J. Jadassohn), pp. 267-289. Springer, Berlin. PIRES DE LIMA, J.A. (1924) Onychatrophie familiale congenitale. Annales de Dermatologie et de Syphiligraphie, 5, 266-271. ROOK, A. (1972) Genetics in Dermatology. In: Textbook of Dermatology (Ed. by A. Rook, D.S. Wilkinson and F.J. Ebling), 2nd edn, vol. i, pp. 105-107. Blackweil Scientific Publications, Oxford. SAMMAN, P . D . (1969) Idiopathic atrophy of the nails. British Journal of Dermatology, 81, 746-749. SAiWMAN, P.D. (1972) The nails in disease, pp. 149-169. William Heinemarm, London. SERTOLI, P. (1956). Eisiopatologia del compksso ungueale, pp. 57-76. Minerva Medica, Torino, Italy. SERTOLI, P. (1974) Patologia delle unghie: ccnni embriogenetici ed istologici, semeiotica e diagnostica generale. Cronica Dermatologica, 3/4, 711-744. SILVERMAN, M.E., GOODMAN, R.M. & CUPPAGE, F . E . (1967) The nail-patella syndrome. Clinical findings and ultrastructural observations in the kidney. Archives of Internal Medicine, 120, 68-74. WEISS, H . & CROSETT, A.D.JR (1955) Chondro-Ectodermal dysplasia. Journal of Pediatrics, 46, 268-275. ZAIAS, N . (1967) The longitudinal nail biopsy. Journal of Investigative Dermatology, 49, 406-408. ZAIAS, N . (1975) Congenital and hereditary diseases involving the nails. In: Clinical Dermatology (Ed. by D.J. Demis, R.G. Crounse, R.L. Dobson and J. McGuire), 3rd edn, vol. i, section 3-3. pp. 1-6. Harper & Row, Maryland, U.S.A.
An unusual congenital nail dystrophy ('soft nail disease')
GIORGIO PRANDI AND MASSIMO CACCIALANZA Clinica Dermatologica, Universita^ di Milano, Via Pace 9, 20122 - Milanoj Italy
Accepted for publication 17 February 1977
Summary An unusual, congenital, non-familial anomaly of all finger and toe nails was observed in a 33-year-old woman. The presence of an atrophic nail plate, which was very soft, has led us to call this condition *soft nail disease'. Histological and histochemical investigations have shown this to be an anatomical and functional defect of the nail matrix which is of unknown origin.
We have recently studied a patient exhibiting an unusual congenital anomaly of the finger and toe nails. All the patient's nails were thin and soft with a short atrophic nail plate and an absent lunula. The plate had no free margin and ended abruptly without a point of separation from the nail bed. This defect, which we have tentatively called 'soft nail disease', should be regarded as an anomalous development of nails. Histological and histochemical investigations have provided some pathogenic clues, allowing some speculations on the anatomical and physiological characteristics of normal nails.
Case Report In June, 1976, a 33-year-oid housewife asked to be treated for a virus wart on her right hand. On examination, it was noted that all her finger and toe nails were abnormal (Fig. i). The nail plate was normally curved and shiny, but was thin and soft. Its antero-posterior diameter W2S shorter than usual. The lunula was absent and the nail plate ended abruptly without any point of separation. The rate of growth of the nail plate could not be determined since the patient's nails had never needed cutting. This pathological condition was responsible for an excessive sensitivity 265
Figure i. App;.arance of the finger nails.
.\.» Figure 2. Longitudinal nail section at the border between intermediate and distal hyponychium showing the abnormal peeling off of the atrophic nail plate (H & E, x ioo).
Unusual congenital nail dystrophy
267
Figure 3. High pov/er view of the nail plate showing the presence of the lower acidophilic layer and the upper basophilic parakeratotic layer (H&E, x 400).
of the distal end of the fingers and the patient had trouble in handling small objects. The defect had been present since birth but was not present in other members of the family. Hair distribution, teeth and sweating appeared to be normal. Physical examination, including radiographs of the skull, elbows, hands, back bone, pelvis and knees showed no
268
G.Prandi and M.Caccialanza
abnormality. The EEG was normal. The caryogram revealed no chromosomal abnormalities. Rheography of the limbs was within normal limits. Mycology of affected nails was negative. A nail biopsy was carried out, according to the method of Zaias (1967). The biopsy fragment was fixed in Bouin's fiuid, embedded in paraffin and easily cut, due to its softness. Sections were stained with hematoxylin-eosin (H & E), periodic acid Schiflf (PAS) and silver impregnation, according to Gomori's method. All the portions of the hyponychium (proximal, intermediate and distal) exhibited a well evident granular layer. The nail plate was atrophic and at the border between the intermediate and distal hyponychium, the nail plate tended to peel off (Fig. 2). Serial sections showed the nail plate to be thin and consisted of two layers: a ventral, thinner, acidophilic layer surmounted by an upper, basophilic parakeratotic layer (Fig. 3). The PAS stain revealed the ventral, thinner one to be PAS positive, and the upper basophilic parakeratotic layer to be PAS negative. Finally, the existence of these two layers was confirmed by the Gomori method, the ventral, thinner layer showing significant argentophilia. Discussion This patient's anomaly ofall nails appeared to be congenital but did not affect other members of the family. It was characterized by atrophy and partial absence of the nail plate, and by total absence of the lunula. We have suggested the term 'soft nail disease' because the nail plate was as soft as normal skin. We have found no reports of a similar anomaly in previous literature (Sertoli, 1956; Pardo-Castello & Pardo-Osvaldo, i960; Samman, 1972; Zaias, 1975). 'Soft nail disease' does not appear to be associated with growth defects and in our opinion should be distinguished from familial onychatrophy which is transmitted to females only (Pires de Lima, 1924); chondro-ectodermal dysplasia (Weiss & Crosett, 1955), brachyonychia (Basset, 1962), congenital dyskeratosis (Milgrom, Stoll& Crissey, 1964), nail-patella syndrome (Silverman, Goodman & Cuppage, 1967); idiopathic nail atrophy (Samman, 1969), hidrotic and anliidrotic ectodermal defects (Rook, 1972); familial pigmentation with nail atrophy (Zaias, 1975). Aetiologically, the dystrophy may result from damage to the 'organizer region'., which controls development of the hyponychium in the embryo. The primary 'organizer', a group of actively proliferating epithelial cells forming a small groove in the proximal portion of the dorsal region of the nail phalanx, is already recognizable toward the middle of the second month of embryonic life (Sertoli, 1974). Damage to this region occurring during the first 6 weeks of pregnancy might, therefore, account for the nail changes observed here. Absence cf the lunula has prompted us to speculate on the possible interpretation of this finding. Pinkus (1927) distinguished three zones in the nail bed: the fertile terminal, the sterile medium and the fertile proximal matrix. They correspond to the distal, intermediate and proximal hyponychium (Sertoli, 1974). Proximal and intermediate hyponchium normally lack the granular layer, which in our patient was preserved. This finding also partially supports the hypothesis of Lewin (1965) who suggested that the white colour of the lunula might be due not only to a loosening of the underlying dermis, but also to an incomplete keratinization of
Unusual congenital nail dystrophy
269
the nail plate. However, our findings appear to contradict both the views of Sertoli (1974) that the colour of the lunula depends upon the presence of keratohyaline granules in the matrix, as well as that of Zaias (1975), who suggested that the colour of the lunula was due to an increased thickness of the matrix itself. The absence of the dorsal layer of the nail plate, which peeled off at the medium third of the hyponychium, indicates a physiological role of this layer in the genesis of the normal nail plate. In agreement with the data reported by Lewis (1954), Achten (1963) and Hashimoto (1971)^ the nail bed generates the ventral portion of the nail plate, which in our patient was represented by a thin horny, acidophilic, PAS positive layer. The overlying layer, in our patient, was largely parakeratotic and peeled off at the medium third of the hyponychium. We believe that this unusual nail dystrophy arises from the absence of the dorsal superficial layer, usually present in the normal nail plate, which controls the compactness of the plate itself.
References ACHTEN, G . (1963) L'ongle normal et pathologique. Dermatologica, 126, 229-245. BASSET, M . R . H . (1962) Trois formes genotypiques d'ongles courts: le pouce en raquette,
le doigts en raquette, les ongles courts simples. Bulletin de la Societe franpaise de Dermatologie et de Syphilographie, 69, 15-20. HASHIMOTO, K . (1971) Ultrastructure of human toe nail. Archiv fiir Dermatologische Eorschung, 240, 1-22.
LEWIN, K . (1965) The normal finger nail. British Journal of Dermatology, 77, 421-430. LEWIS, B.L. (1954) Microscopic studies of foetal and mature nail and surrounding soft tissue.
Archives of Dermatology, 70, 732-747. MILGROM, H . , STOLL, H.L.JR & CRISSEY, J . T . (1964) Dyscheratosis congenita. Archives of Dermatology, 89, 345-349. PARDO-CASTELLO, V. & PARDO-OSVALDO, A. (i960) Diseases of the nails (Ed. by V. Pardo-Castello and A. Pardo-Osvaldo), 3rd edn, pp. 220-233. Charles C. Thomas, Springfield, Illinois. PINKUS, F . (1927) Der Nagel. In; Handbuch der Haut und Geschlechtskrakeiten (Ed. by J. Jadassohn), pp. 267-289. Springer, Berlin. PIRES DE LIMA, J.A. (1924) Onychatrophie familiale congenitale. Annales de Dermatologie et de Syphiligraphie, 5, 266-271. ROOK, A. (1972) Genetics in Dermatology. In: Textbook of Dermatology (Ed. by A. Rook, D.S. Wilkinson and F.J. Ebling), 2nd edn, vol. i, pp. 105-107. Blackweil Scientific Publications, Oxford. SAMMAN, P . D . (1969) Idiopathic atrophy of the nails. British Journal of Dermatology, 81, 746-749. SAiWMAN, P.D. (1972) The nails in disease, pp. 149-169. William Heinemarm, London. SERTOLI, P. (1956). Eisiopatologia del compksso ungueale, pp. 57-76. Minerva Medica, Torino, Italy. SERTOLI, P. (1974) Patologia delle unghie: ccnni embriogenetici ed istologici, semeiotica e diagnostica generale. Cronica Dermatologica, 3/4, 711-744. SILVERMAN, M.E., GOODMAN, R.M. & CUPPAGE, F . E . (1967) The nail-patella syndrome. Clinical findings and ultrastructural observations in the kidney. Archives of Internal Medicine, 120, 68-74. WEISS, H . & CROSETT, A.D.JR (1955) Chondro-Ectodermal dysplasia. Journal of Pediatrics, 46, 268-275. ZAIAS, N . (1967) The longitudinal nail biopsy. Journal of Investigative Dermatology, 49, 406-408. ZAIAS, N . (1975) Congenital and hereditary diseases involving the nails. In: Clinical Dermatology (Ed. by D.J. Demis, R.G. Crounse, R.L. Dobson and J. McGuire), 3rd edn, vol. i, section 3-3. pp. 1-6. Harper & Row, Maryland, U.S.A.
