CYTOLOGIC DIAGNOSIS OF MELANOMA IN SEROUS EFFUSIONS - A MORPHOLOGIC AND IMMUNOCYTOCHEMICAL STUDY

The diversity of melanoma patterns greatly impairs the interpretation of malignant cells in effusion samples. The presence of melanin pigmen ts greatly helps determine the histogenetic origin of the tumor, but u nfortunately many cases do not exhibit this feature. We reviewed cases with a definitive diagnosis of melanomia in order to identify some us eful characteristics of the morphologic examination of effusions. We a lso subjected the effusions to the HMB45 immunoreaction to determine t he diagnostic usefulness of this monoclonal antibody. The study was pe rformed on 21 effusion samples containing malignant (c)ells, and the m ain cytologic findings were similar to those on other neoplasms except for the presence of melanin pigment. The HMB45 immunoreaction was ver y sensitive, confirming the diagnosis in 14 of 18 cases (77.8%). Melan in pigments seem to be useful markers for melanoma in effusions, and H MB45 can be used as an ancillary method in the differential diagnosis.