A clinicopathologic study of malignant melanoma based on cytomorphology

Melanoma accounts for 1-3% of all malignancies. It is usually diagnosed as metastasis in the draining lymph nodes, that is inguinal lymph node. Due to paucity of cytological studies on melanoma in India, the present study was undertaken.

To study the cytomorphology of malignant melanoma and to correlate the cytological diagnosis with histopathology and clinical details.

Sixteen cytomorphological features were studied and analysed from the cases diagnosed as melanoma on cytology with histopathological correlation.

Thirty patients diagnosed with malignant melanoma on fine-needle aspiration cytology (FNAC) were studied over a period of 10 years and compared by histopathology. Papanicolaou (Pap)- and May Grunwald Giemsa (MGG)-stained smears were studied and analysed for the cytomorphological spectrum of melanoma.

Among the 30 patients studied, males were 19 and females were 11 (M:F:1.7:1) with a mean age of 49.3 years. The commonest primary site was foot followed by maxilla and thigh. The most common site for metastasis was inguinal lymph node. All 30 cases had histopathological correlation. Pigmented melanophages (83%) was the predominant feature followed by presence of melanin pigment (77%) and pseudo-inclusions (73%). Condensed chromatin was observed in the majority of the patients (53%). Smooth and irregular nuclear contours were seen in combination in 37% of the cases. A combination of nuclear placement, that is eccentric and central was observed as a predominant feature (53%). Spindle cell pattern was the predominant shape. Among cytoplasmic features, melanin granules and vacuoles were equally distributed (50%). Mixed pattern, that is singly scattered plasmacytoid cell pattern and cell clusters was the predominant cell architecture.

A spectrum of cytomorphological features in correlation with clinical details leads to greater precision in diagnosis and helps to avoid pitfalls in diagnosing melanoma.