Pathology Quiz Case/Pathology Quiz Case: Diagnosis

• Published in: Archives of otolaryngology--head & neck surgery Vol. 132; no. 3; p. 349
• Main Authors: Nowlin, Thomas P, Freeman, Judy H, Cable, Benjamin
• Format: Journal Article
• Language: English
• Published: Chicago American Medical Association 01-03-2006
• Subjects: Biopsy; Cancer; Children & youth; Lymphatic system; Monoclonal antibodies
• ISSN: 2168-6181; 2168-619X

The diagnosis of a Spitz nevus depends on an assessment of multiple morphological features, including cell type (epithelioid and/or spindle cell), symmetrical appearance of the lesion, maturation of the nevus cells, lack of paget-oid spread of single melanocytes, and presence of coalescent eosinophilic globules (Kamino bodies). Tumors in the atypical category are more apt to present with central ulceration or large size (>1 cm).12 Histologic features of atypical lesions include an abnormally high mitotic rate, lack of melanocyte maturity, increased cellularity, and deep extension into the subcutaneous fat. Immunohistochemical studies may be helpful but not definitive in differentiating between melanoma and Spitz nevi.12-14 Spitz nevi are diffusely positive for S100 protein, but HMB-45 staining tends to be distributed to the junctional component and the superficial dermal component.13 They also tend to test positive for HLA-ABC and negative for HLA-DR.7 Human monoclonal antibody 2-139-1, which reflects an early event in melanocytic tumor progression, may help separate Spitz lesions from melanoma.14 Although these special stains can aid in diagnosis, there is no definitive pathognomonic test in our armamentarium at this time.