Case Report
Hyalinizing Spitz Nevus: Spindle and Epithelioid Cell Nevus with Paucicellular Collagenous Stroma
Abstract
Hyalinizing spindle and epithelioid cell nevus (Spitz nevus) is an uncommon melanocytic lesion. The histologic features of this benign tumor can mimic those of certain benign (dermatofibroma and desmoplastic cellular blue nevus) and malignant (metastatic carcinoma and malignant melanoma) neoplasms. We report a woman with a hyalinizing Spitz nevus and review the clinical characteristics, histologic features, and differential diagnosis of this lesion. The lesion presented as an asymptomatic red firm nodule on her abdomen. Microscopic examination showed a symmetric lesion in the dermis. The neoplastic cells were large and epithelioid-shaped or plump and spindle-shaped. They were present as isolated individual cells, single cells in a linear pattern, small nests, and fascicles in a paucicellular hyalinized stroma. Neoplastic cells with prominent eosinophilic nucleoli were evenly exhibited from the superficial to deep lesion. Diffuse expression of S-100 protein and absence of staining with antibodies to cytokeratin and HMB-45 were observed. The features were diagnostic of a hyalinizing Spitz nevus. Hyalinizing Spitz nevus is a benign lesion whose histologic features may mimic dermatofibroma, desmoplastic cellular blue nevus, metastatic carcinoma, and malignant melanoma. Immunohistochemical studies are helpful to differentiate these lesions.
Spitz nevus is a benign and usually acquired melanocytic nevus. It typically consists of spindle and epithelioid cells in a vascular and edematous stroma. Suster, 1 in 1994, described a variant of Spitz nevi characterized by Spitz nevus cells in a paucicellular dermal stroma. These lesions were called hyalinizing spindle and epithelioid cell nevus, thereby adding a new category to the previously described unusual variants of Spitz nevi (Table 1). 1–18 In this paper, we report a woman with a hyalinizing Spitz nevus and review the clinical features and histologic differential diagnosis of this lesion.
Table 1
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