Skin Cancer Research Today is a free monthly online journal that collates and summarizes the latest research about Skin Cancer, including details on identification, causes, prevention, treatment.

Frequent positive staining with NKI/C3 in normal and neoplastic tissues limits its usefulness in the diagnosis of cellular neurothekeoma.

Sachdev R, Sundram UN

Department of Pathology, Stanford University Medical Center, Stanford, CA 94305, USA.

NKI/C3 originally was described as a marker for melanoma. Recently, it resurfaced as a marker to separate cellular neurothekeoma from other dermal tumors in the differential diagnosis. To determine the sensitivity and specificity of NKI/C3, we evaluated its staining pattern in 709 normal and neoplastic tissues, including 92 dermal tumors, using tissue microarrays and conventional sections. We found that although NKI/C3 is positive in only a few normal tissues, it stains a broad spectrum of neoplastic tissues. NKI/C3 is also positive in many dermal tumors of possible histiocytic origin, including juvenile xanthogranuloma (6/10), atypical fibroxanthoma (4/12), cellular fibrous histiocytoma (5/10), reticulohistiocytoma (3/6), and xanthoma (8/10). However, it is negative in epithelioid cell histiocytomas (0/7) and Langerhans cell histiocytosis (0/9). Given the wide spectrum of positive staining in morphologic mimics of cellular neurothekeomas, pathologists should be cautious when making this diagnosis based solely on positive staining with NKI/C3.

Published 29 August 2006 in Am J Clin Pathol, 126(4): 554-63.
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