CELLULAR BLUE NEVUS WITH MASSIVE REGIONAL LYMPH-NODE METASTASES

BACKGROUND. Small, well-differentiated groups of nevus cells have been found occasionally in the marginal sinuses and parenchyma of regional lymph nodes that drain sites of cellular blue nevi. OBJECTIVE. The hi stologic, immunohistochemical, and karyometric description of a pigmen ted cutaneous lesion, with the features of cellular blue nevus and loc ated on the leg of a 14-year-old woman, that was accompanied by synchr onic presentation of massive inguinal lymph-node metastases. METHODS. The excised specimens were processed routinely, embedded in paraffin, and sectioned into 4-mu m-thick slices. The sections were stained usin g hematoxylin-eosin and the ABC immunohistochemical method for demonst rating S-100 and HMB-45. Karyometric analysis was performed in a stati c cytometer using Feulgen-stained sections. RESULTS. The cutaneous les ion had the cytologic and architectural features of cellular blue nevu s. The lymph nodes showed massive invasion by pigmented cells and cont ained extensive necrotic foci. After 3.5 years of clinical follow-up, the patient is free from disease. CONCLUSIONS. The absence of malignan t features in the cuta'neous lesion and the bland nuclear features of the pigmented cells in the regional lymph node metastases suggest that this case could be interpreted as an unusual form of benign cellular blue nevus with metastases. Nonetheless, other possibilities, such as malignant melanoma mimicking a cellular blue nevus or primary malignan t melanoma of the lymph nodes with concomitant cutaneous cellular blue nevus, cannot be definitively excluded. A conservative surgical appro ach with close follow-up was recommended.