Pigmented spindle cell nevus: a clinicopathologic analysis of ninety-five cases.

Abstract

Pigmented spindle cell nevus (PSCN) is often interpreted as a Spitz nevus or misdiagnosed as malignant melanoma. The purpose of this study was to analyze the clinical and histologic features and to determine the biologic behavior of 95 cases of PSCN. We reviewed clinical data, follow-up information, and microscopic features of all 95 cases of PSCN. PSCNs are dark brown to black, 3 to 6 mm in diameter, and occur most commonly on the extremities (75%) and back (16%) with a predilection for the legs. These lesions are more common in women in the third decade of life. Microscopically, PSCNs are characterized by uniform, spindle-shaped, pigmented melanocytes. Although some histologic features overlap with those in spindle and epithelioid cell nevus, PSCN is a separate entity. In addition, PSCN must be differentiated from malignant melanoma. Fifty-seven patients (60%) observed for an average of 6 years did not develop local recurrence or metastasis. PSCN is a distinctive, acquired, benign melanocytic lesion, that should not be confused with spindle and epithelioid cell nevus or malignant melanoma. Complete excision is recommended for treatment.