Desmoplastic cellular neurothekeoma: Clinicopathological analysis of twelve cases.

BACKGROUND: Cellular neurothekeoma is a benign lesion most commonly found on the face and upper extremities in the first two decades of life.

METHODS: Retrospective clinicopathologic review of 12 examples of cellular neurothekeoma typified by prominent stromal sclerosis, a distinctive variant that we refer to as desmoplastic cellular neurothekeoma.

RESULTS: The mean age was 30 years (range, 3-55 years, 3 males, 9 females). The site was the head and neck in 3 cases, upper extremity in 4, lower extremity in 2, and trunk/abdomen in 3. All cases showed fascicles of slightly spindled and polygonal cells arrayed haphazardly in a prominent sclerotic background in the dermis and superficial subcutis. The cells displayed pale cytoplasm with indistinct membranes and vesicular nuclei with a single nucleolus. Lesional cells expressed NKI/C3, laminin, CD68, and CD10 and lacked expression of S-100 protein, EMA, and CD34. Clinical follow up was available on 10 cases with a mean duration of 24 months (range, 11-42 months) with no local recurrences or metastases.

CONCLUSIONS: The immunohistochemical staining pattern, clinical findings, and benign nature are similar to "conventional" cellular neurothekeomas. The differential diagnosis includes desmoplastic melanocytic lesions, desmoplastic spindle cell carcinoma, dermatofibroma, "immature" scar, plexiform fibrohistiocytic tumor, perineurioma, and piloleiomyoma.