APMIS 122: 1045–1046
© 2014 APMIS. Published by John Wiley & Sons Ltd. DOI 10.1111/apm.12259
Letter to the Editor Dirofilaria repens mimicking an ovarian mass: histologic and molecular diagnosis To the Editor Human dirofilariasis is a parasitic vector-borne zoonosis caused by nematodes of the genus Dirofilaria (Filarioidea: Onchocercidae), often mimicking tumor-like lesions (1–11). In the Old World, human dirofilariasis is an emergent vector-borne zoonosis (1, 10). We describe the first human ovarian localization of D. repens, mimicking a tumor lesion. A 52-year-old woman was admitted to Novara Hospital (Italy) to undergo left laparoscopic salpingo-oophorectomy for an ovarian mass, identified by ultrasounds during a routine follow-up examination. At the pre-operative ultrasound examination, left ovary showed an irregular outline, almost completely replaced by a cystic mass of 43 9 27 mm. The surgical specimen was fixed in 10% buffered formalin and processed routinely. Paraffin-embedded blocks were sectioned and stained with hematoxylin and eosin, Weigert’s stain, Mallory’s and Masson’s Trichrome. The surgical specimen included left ovary, salpinx, and a whitish ovarian nodule of about 1 cm in diameter. In light microscopy, the latter was composed of a folded-up necrotic nematode, embedded within abundant ischemic necrosis and surrounded by dense band of fibrosis (Fig. 1). A benign Brenner tumor was also identified in the remaining ovarian parenchyma. A regular wavy cuticular surface with external longitudinal ridges
around the entire circumference of the worm was enhanced by Mallory’s and Masson’s Trichrome (Fig. 2). The worm’s dimension (major diameter of about 325–559 lm in most preserved transverse and oblique sections) and the presence of a regressive single genital tubule containing spermatocyticlike formations were consistent with a male adult worm (Fig. 2). An initial diagnosis of a D. repens infection was made, mainly based on cuticular morphology, worm’s diameters, and our previous experience with other cases of dirofilariasis (2, 4). Polymerase chain reaction (PCR) (4) amplified a 246-base pair product (specific for D. repens), confirming our histological suspect. Italy has one of the highest prevalences of dirofilariasis in Western countries and D. repens is endemic in Piedmont, where our patient lives and where the presence of many rice fields, small artificial lakes, and stagnant pools favors mosquito’s growth (2, 4, 5). Human dirofilariasis is often asymptomatic or symptoms could be unnoticed or misinterpreted, with literature underreporting (3). Clinical presentations of D. repens are usually subcutaneous or ocular (1–5, 8–11). Conversely, rare unusual deep localizations are incidentally found or clinically misdiagnosed for benign or malignant lesions (2–5, 7–9, 11). In our case, the concomitant presence of the parasitic nodule with the benign Brenner tumor was globally misinterpreted as a single mass with not clearly benign features at ultrasounds. Moreover, the presence of a peripheral fibrotic wall enclosing the necrotic nematode could have been misinterpreted in ultrasound
Fig. 1. Sections of a folded-up necrotic nematode embedded in a context of abundant eosinophilic ischemic necrosis. The worm shows an indented cuticular surface, whereas internal organs showed signs of regression and vacuolization. Haematoxylin and Eosin, 910.
Fig. 2. Longitudinal, transverse, and oblique sections of the necrotic nematode, in a context of abundant ischemic necrosis. Masson’s Trichrome, 910.
1045
LETTER TO THE EDITOR
examination as the cystic portion of the suspected lesion (11). Dirofilaria’s body diameter and cuticular morphology are the most important elements for differential diagnosis (1–11): the diameters of the nematode fitted the microscopic dimensional range of a D. repens, showing a typically indented cuticular surface (1–9, 11). Regressive or necrotic condition of the nematode due to inflammatory host response, its frequent immature stage in humans and various orientation of worm’s microscopic sections could be responsible for literature variability in reported parasitic size and for a possible difficult histological identification of Dirofilaria’s morphology, sex, and maturation grade (2, 4, 5, 7–9, 11), as in our case. Moreover, a deep-located tumor-like necrotic, inflammatory or fibrous nodule could reveal the worm’s presence only after multiple seriated sections, with a possible misdiagnosis especially at intra-operatory pathological consult (2–5, 7–9, 11). Finally, we stress the importance of the use of molecular approach not only when morphological features of the parasite are not recognizable for its degenerated or regressive condition, but also for a more accurate diagnosis in morphologically preserved cases. PCR amplification analysis is of fundamental help: minimal quantities of DNA could result in positive reactions (3), even in formalin-fixed and paraffin-embedded necrotic samples. In conclusion, anamnestic data (countries visited by the patient or place of living) are important to orient the clinico-pathological suspect, even if climate changes and globalization with international movements of humans, vectors, and reservoir animals seem to produce not only an increase in incidence in endemic regions, but also new cases in previously diseasefree areas (3). In endemic regions, the familiarity with histological presentation of dirofilariasis and the fundamental aid of PCR analysis could favor a more accurate parasite identification and an increased reporting of classical and perhaps unusual localization, but it could also avoid more serious misdiagnosis, especially in unusual deep localizations with a clinical suspect of possible malignancy.
CONFLICTS OF INTEREST The authors declare that they have no conflict of interest. ANDREA PALICELLI1 CRISTINA DEAMBROGIO,1 ALBERTO ARNULFO,2 FRANCESCO RIVASI,3 ALESSIA PAGANOTTI4 and RENZO BOLDORINI1,4
1046
1
Department of Health Science, School of Medicine, University of Eastern Piedmont “Amedeo Avogadro”, Novara; 2Unit of Obstetrics and Gynecology, Maggiore Hospital, Novara; 3 Department of Diagnostic Medicine and Public Health, University of Modena and Reggio Emilia Modena; and 4Unit of Pathology, Maggiore Hospital, Novara, Italy E-mail: [email protected]
REFERENCES 1. Genchi C, Kramer LH, Rivasi F. Dirofilarial infections in Europe. Vector Borne Zoonotic Dis 2011;11:1307–17. 2. Pampiglione S, Rivasi F, Angeli G, Boldorini R, Incensati RM, Pastormerlo M, et al. Dirofilariasis due to Dirofilaria repens in Italy, an emergent zoonosis: report of 60 new cases. Histopathology 2001;38:344–54. 3. Sim on F, Siles-Lucas M, Morch on R, Gonz alezMiguel J, Mellado I, Carret on E, et al. Human and animal dirofilariasis: the emergence of a zoonotic mosaic. Clin Microbiol Rev 2012;25: 507–44. 4. Rivasi F, Boldorini R, Criante P, Leutner M, Pampiglione S. Detection of Dirofilaria (Nochtiella) repens DNA by polymerase chain reaction in embedded paraffin tissues from two human pulmonary locations. APMIS 2006;114:567–74. 5. Pampiglione S, Rivasi F. Human dirofilariasis due to Dirofilaria (Nochtiella) repens: an update of world literature from 1995 to 2000. Parassitologia 2000;42:231–54. 6. Canestri-Trotti G, Pampiglione S, Rivasi F. The species of the genus Dirofilaria, Railliet & Henry, 1911. Parassitologia 1997;39:369–74. 7. Orihel TC, Eberhard ML. Zoonotic filariasis. Clin Microbiol Rev 1998;11:366–81. 8. Pampiglione S, Rivasi F, Gustinelli A. Dirofilarial human cases in the Old World, attributed to Dirofilaria immitis: a critical analysis. Histopathology 2009;54:192–204. 9. Pampiglione S, Rivasi F, Canestri-Trotti G. Pitfalls and difficulties in histological diagnosis of human dirofilariasis due to Dirofilaria (Nochtiella) repens. Diagn Microbiol Infect Dis 1999;34: 57–64. 10. Bockov a E, Rudolf I, Kocisov a A, Bet asov a L, Venclıkov a K, Mendel J, et al. Dirofilaria repens microfilariae in Aedes vexans mosquitoes in Slovakia. Parasitol Res 2013;112:3465–70. 11. Pampiglione S, Canestri Trotti G, Rivasi F. Human dirofilariasis due to Dirofilaria (Nochtiella) repens: a review of world literature. Parassitologia 1995;37:149–93.
© 2014 APMIS. Published by John Wiley & Sons Ltd
© 2014 APMIS. Published by John Wiley & Sons Ltd. DOI 10.1111/apm.12259
Letter to the Editor Dirofilaria repens mimicking an ovarian mass: histologic and molecular diagnosis To the Editor Human dirofilariasis is a parasitic vector-borne zoonosis caused by nematodes of the genus Dirofilaria (Filarioidea: Onchocercidae), often mimicking tumor-like lesions (1–11). In the Old World, human dirofilariasis is an emergent vector-borne zoonosis (1, 10). We describe the first human ovarian localization of D. repens, mimicking a tumor lesion. A 52-year-old woman was admitted to Novara Hospital (Italy) to undergo left laparoscopic salpingo-oophorectomy for an ovarian mass, identified by ultrasounds during a routine follow-up examination. At the pre-operative ultrasound examination, left ovary showed an irregular outline, almost completely replaced by a cystic mass of 43 9 27 mm. The surgical specimen was fixed in 10% buffered formalin and processed routinely. Paraffin-embedded blocks were sectioned and stained with hematoxylin and eosin, Weigert’s stain, Mallory’s and Masson’s Trichrome. The surgical specimen included left ovary, salpinx, and a whitish ovarian nodule of about 1 cm in diameter. In light microscopy, the latter was composed of a folded-up necrotic nematode, embedded within abundant ischemic necrosis and surrounded by dense band of fibrosis (Fig. 1). A benign Brenner tumor was also identified in the remaining ovarian parenchyma. A regular wavy cuticular surface with external longitudinal ridges
around the entire circumference of the worm was enhanced by Mallory’s and Masson’s Trichrome (Fig. 2). The worm’s dimension (major diameter of about 325–559 lm in most preserved transverse and oblique sections) and the presence of a regressive single genital tubule containing spermatocyticlike formations were consistent with a male adult worm (Fig. 2). An initial diagnosis of a D. repens infection was made, mainly based on cuticular morphology, worm’s diameters, and our previous experience with other cases of dirofilariasis (2, 4). Polymerase chain reaction (PCR) (4) amplified a 246-base pair product (specific for D. repens), confirming our histological suspect. Italy has one of the highest prevalences of dirofilariasis in Western countries and D. repens is endemic in Piedmont, where our patient lives and where the presence of many rice fields, small artificial lakes, and stagnant pools favors mosquito’s growth (2, 4, 5). Human dirofilariasis is often asymptomatic or symptoms could be unnoticed or misinterpreted, with literature underreporting (3). Clinical presentations of D. repens are usually subcutaneous or ocular (1–5, 8–11). Conversely, rare unusual deep localizations are incidentally found or clinically misdiagnosed for benign or malignant lesions (2–5, 7–9, 11). In our case, the concomitant presence of the parasitic nodule with the benign Brenner tumor was globally misinterpreted as a single mass with not clearly benign features at ultrasounds. Moreover, the presence of a peripheral fibrotic wall enclosing the necrotic nematode could have been misinterpreted in ultrasound
Fig. 1. Sections of a folded-up necrotic nematode embedded in a context of abundant eosinophilic ischemic necrosis. The worm shows an indented cuticular surface, whereas internal organs showed signs of regression and vacuolization. Haematoxylin and Eosin, 910.
Fig. 2. Longitudinal, transverse, and oblique sections of the necrotic nematode, in a context of abundant ischemic necrosis. Masson’s Trichrome, 910.
1045
LETTER TO THE EDITOR
examination as the cystic portion of the suspected lesion (11). Dirofilaria’s body diameter and cuticular morphology are the most important elements for differential diagnosis (1–11): the diameters of the nematode fitted the microscopic dimensional range of a D. repens, showing a typically indented cuticular surface (1–9, 11). Regressive or necrotic condition of the nematode due to inflammatory host response, its frequent immature stage in humans and various orientation of worm’s microscopic sections could be responsible for literature variability in reported parasitic size and for a possible difficult histological identification of Dirofilaria’s morphology, sex, and maturation grade (2, 4, 5, 7–9, 11), as in our case. Moreover, a deep-located tumor-like necrotic, inflammatory or fibrous nodule could reveal the worm’s presence only after multiple seriated sections, with a possible misdiagnosis especially at intra-operatory pathological consult (2–5, 7–9, 11). Finally, we stress the importance of the use of molecular approach not only when morphological features of the parasite are not recognizable for its degenerated or regressive condition, but also for a more accurate diagnosis in morphologically preserved cases. PCR amplification analysis is of fundamental help: minimal quantities of DNA could result in positive reactions (3), even in formalin-fixed and paraffin-embedded necrotic samples. In conclusion, anamnestic data (countries visited by the patient or place of living) are important to orient the clinico-pathological suspect, even if climate changes and globalization with international movements of humans, vectors, and reservoir animals seem to produce not only an increase in incidence in endemic regions, but also new cases in previously diseasefree areas (3). In endemic regions, the familiarity with histological presentation of dirofilariasis and the fundamental aid of PCR analysis could favor a more accurate parasite identification and an increased reporting of classical and perhaps unusual localization, but it could also avoid more serious misdiagnosis, especially in unusual deep localizations with a clinical suspect of possible malignancy.
CONFLICTS OF INTEREST The authors declare that they have no conflict of interest. ANDREA PALICELLI1 CRISTINA DEAMBROGIO,1 ALBERTO ARNULFO,2 FRANCESCO RIVASI,3 ALESSIA PAGANOTTI4 and RENZO BOLDORINI1,4
1046
1
Department of Health Science, School of Medicine, University of Eastern Piedmont “Amedeo Avogadro”, Novara; 2Unit of Obstetrics and Gynecology, Maggiore Hospital, Novara; 3 Department of Diagnostic Medicine and Public Health, University of Modena and Reggio Emilia Modena; and 4Unit of Pathology, Maggiore Hospital, Novara, Italy E-mail: [email protected]
REFERENCES 1. Genchi C, Kramer LH, Rivasi F. Dirofilarial infections in Europe. Vector Borne Zoonotic Dis 2011;11:1307–17. 2. Pampiglione S, Rivasi F, Angeli G, Boldorini R, Incensati RM, Pastormerlo M, et al. Dirofilariasis due to Dirofilaria repens in Italy, an emergent zoonosis: report of 60 new cases. Histopathology 2001;38:344–54. 3. Sim on F, Siles-Lucas M, Morch on R, Gonz alezMiguel J, Mellado I, Carret on E, et al. Human and animal dirofilariasis: the emergence of a zoonotic mosaic. Clin Microbiol Rev 2012;25: 507–44. 4. Rivasi F, Boldorini R, Criante P, Leutner M, Pampiglione S. Detection of Dirofilaria (Nochtiella) repens DNA by polymerase chain reaction in embedded paraffin tissues from two human pulmonary locations. APMIS 2006;114:567–74. 5. Pampiglione S, Rivasi F. Human dirofilariasis due to Dirofilaria (Nochtiella) repens: an update of world literature from 1995 to 2000. Parassitologia 2000;42:231–54. 6. Canestri-Trotti G, Pampiglione S, Rivasi F. The species of the genus Dirofilaria, Railliet & Henry, 1911. Parassitologia 1997;39:369–74. 7. Orihel TC, Eberhard ML. Zoonotic filariasis. Clin Microbiol Rev 1998;11:366–81. 8. Pampiglione S, Rivasi F, Gustinelli A. Dirofilarial human cases in the Old World, attributed to Dirofilaria immitis: a critical analysis. Histopathology 2009;54:192–204. 9. Pampiglione S, Rivasi F, Canestri-Trotti G. Pitfalls and difficulties in histological diagnosis of human dirofilariasis due to Dirofilaria (Nochtiella) repens. Diagn Microbiol Infect Dis 1999;34: 57–64. 10. Bockov a E, Rudolf I, Kocisov a A, Bet asov a L, Venclıkov a K, Mendel J, et al. Dirofilaria repens microfilariae in Aedes vexans mosquitoes in Slovakia. Parasitol Res 2013;112:3465–70. 11. Pampiglione S, Canestri Trotti G, Rivasi F. Human dirofilariasis due to Dirofilaria (Nochtiella) repens: a review of world literature. Parassitologia 1995;37:149–93.
© 2014 APMIS. Published by John Wiley & Sons Ltd
