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Perineuriomatous nevi: A series of eight cases highlighting unifying pathologic features to avoid misdiagnosis
Author(s) -
McAfee John L.,
Dermawan Josephine K.,
Billings Steven D.,
Ko Jennifer S.
Publication year - 2021
Publication title -
journal of cutaneous pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 75
eISSN - 1600-0560
pISSN - 0303-6987
DOI - 10.1111/cup.14014
Subject(s) - pathology , medicine , pleomorphism (cytology) , nevus , differential diagnosis , cd34 , blue nevus , melanoma , biology , immunohistochemistry , stem cell , cancer research , genetics
Abstract Background Perineuriomatous nevi are rare and diagnostically problematic. We report a series of eight perineuriomatous nevi to highlight the diagnostic features. Methods Cases were retrospectively reviewed and characterized. Results Median age was 42.5 years (range 25‐64), with equal sex distribution. Lesions occurred on the arm (n = 4), trunk (n = 2), and head/neck (n = 2). Median size was 7.5 mm (range 5‐12 mm). Clinical differential diagnoses included atypical nevus (3), blue nevus (1), neurofibroma (1), and dermatofibroma (1). Lesions were circumscribed, dome‐shaped (5/8), and biphasic (8/8) with nested epithelioid cells and wavy spindled cells arranged in whorled fascicles in a myxocollagenous stroma. When present, junctional growth was lentiginous (4/8). No cases displayed pleomorphism or mitotic figures. The perineuriomatous component stained positively for epithelial membrane antigen (8/8 focal to diffuse) and CD34 (4/5 focal to diffuse). SOX10 and S100 protein stained all nevoid cells and in some cases a subset of intermingled spindled cells in perineuriomatous areas, where other melanocytic markers were negative. p16 protein expression was uniformly retained (3/3), and p53 negative (0/2). Nevoid cells in most lesions were positive for BRAFV600E (5/7). Ki67 was mildly elevated (~5%) in 3/3 cases. Conclusions Recognizing the histopathologic and immunophenotypic features in these unusual nevi helps avoid overdiagnosis.