Cytoplasmic vacuoles: clue in the fine-needle aspiration diagnosis of melanoma.

For the fine-needle aspiration (FNA) diagnosis of melanoma recognition of characteristic morphologic features is key. In our practice we noted that cytoplasmic vacuoles in Romanowsky-stained FNA smears of melanoma appeared to be a frequent finding. To investigate this premise, we examined 36 consecutive melanoma FNA cases that had both adequate Papanicolaou-stained and Romanowsky-stained smears in an effort to determine the prevalence, and thereby, the potential diagnostic utility of cytoplasmic vacuoles in the diagnosis of melanoma compared to established cytomorphologic parameters of melanoma. We found pigment in 21 cases (58%) and plasmacytoid cells in 28 cases (78%), and in all 36 cases (100%) we found bi/multinucleation, intranuclear cytoplasmic inclusions and prominent nucleoli. Cytoplasmic vacuoles were present in 30 cases (83%) and were found in air-dried Romanowsky-stained smears only. These findings suggest that in FNA smears of melanoma cytoplasmic vacuoles in Romanowsky-stained smears have prevalence and potential diagnostic utility that are comparable to widely recognized cytomorphologic features of melanoma. Numerous articles have focused on the cytomorphologic criteria for the FNA diagnosis of melanoma, but few have noted the presence of cytoplasmic vacuoles in FNA smears of melanoma, and rare reports suggest this finding to be a useful clue to the FNA diagnosis of melanoma. This report appears to be the first to focus on the prevalence and potential diagnostic utility of cytoplasmic vacuoles in FNA samples of melanoma.