NUCLEOLAR ORGANIZER REGIONS AND IMAGE-ANALYSIS NUCLEAR MORPHOMETRY OFSMALL-CELL (NEVOID) MELANOMA

Small cell (nevoid) melanomas may provide difficulties in diagnosis as their constituent cell type resembles a benign nevoid melanocyte. In the present study, 10 small cell melanomas were analyzed for the silve r staining of their nucleolar organizing regions (AgNORs), and their n uclear area and perimeter were measured by computerized digital image analysis and compared with TO superficial spreading melanomas lacking small cell differentiation and 10 dermal nevi. The average number of A gNORs per nucleus was 5.83 (SD +/- 1.69) for small cell melanomas and was significantly different when compared with 8.49 (SD +/- 1.58) for superficial spreading melanomas (p < 0.05) and 2.71 (SD +/- 0.50) for dermal nevi (p < 0.05). Digital image analysis confirmed that the nucl ear perimeter and nuclear area of cells in nevoid melanomas did not si gnificantly differ from those of ordinary dermal nevi (p > 0.05), but both group were significantly different from superficial spreading mel anomas lacking a small cell morphology (P < 0.05). Counting AgNOR numb ers may be useful in evaluating small cell (nevoid) melanomas and prov ides a technique for differentiating their constituent cell from ordin ary nevus cells. Nuclear morphometry determined by digital image analy sis may help better define the nuclear size in small cell melanomas.