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

Background: Pigmented spindle cell nevus (PSCN) is often interpreted as a Spitz nevus or misdiagnosed as malignant melanoma.

Objective: The purpose of this study was to analyze the clinical and histologic features and to determine the biologic behavior of 95 cases of PSCN.

Methods: We reviewed clinical data, follow-up information, and microscopic features of all 95 cases of PSCN.

Results: 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.

Conclusions: 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.