SINONASAL MALIGNANT-MELANOMA - A CLINICOPATHOLOGICAL ANALYSIS OF 18 CASES

Sinonasal melanoma is a rare malignancy. We present the clinicopatholo gic review of 18 cases seen at the British Columbia Cancer Agency betw een 1976 and 1992: 13 men and five women, mean age 66 years (range 32- 88). Patients presented with nasal obstruction and bleeding (n = 8), o bstruction alone (n = 4), bleeding alone (n = 5) or pain (n = 1). Thos e with bleeding presented with a shorter duration of symptoms than tho se with obstruction alone. All patients with obstruction alone died of their disease, while all patients with bleeding alone are alive or ha ve died of an unrelated cause; four out of eight patients with both ob struction and bleeding are alive. There was no significant relationshi p between treatment modality and outcome. Histologic subtypes included epithelioid (n = 10), spindle-cell (n = 4), small-cell (n = 3) and pl eomorphic (n = 1). Eight out of 11 cases from whom samples of paraffin -embedded tissue were available showed more prominent staining for HMB -45 than for S-100. In two cases, only rare (<0.1%) cells stained for S-100. Cell type, mitotic rate and P53 expression were unrelated to di sease outcome. Six out of seven patients with less than or equal to 10 % of cells showing intense staining for PCNA were alive or had died of an unrelated cause, while three out of four with >10% staining died o f their disease. These data suggest that presentation with bleeding an d a low degree of staining for PCNA may be favourable prognostic facto rs in sinonasal melanoma, and that HMB-45 may be a more sensitive mark er than S-100 for melanocytic differentiation in sinonasal neoplasms.