Abstract
A case report of malignant melanoma arising from male urethra was presented, urinary cytological material and stamp smear from the tumor was examined in addition to ultrastructural study of the recurrent tumor of the melanoma.
The patient was a 70-year-old male. Complaining of pollakiuria, dysuria, and hematuria, he visited the clinic of urology. The urethral tumor was found and histopathologically diagnosed as malignant melanoma.
Many tumor cells were observed upon urinary cytology after operation. Most of the tumor cells were solitary and scattered. Large nuclei with prominent nucleoli were eccentrically located in the cytoplasm. The cytoplasm contained a small number of melanin granules. The cells scanty in melanin granules were similar to those of a adenocarcinoma.
Ultrastructurally, the tumor cells had numerous melanosomes in the cytoplasm which were mostly type 1 and 2, with some of type 3 and 4.
The intranuclear vacuoles stained with light green for Papanicolaou's staining were often seen, but under electron microscope the vascuoles were thought to be intranuclear invagination which was well defined with a nuclear membrane, they contained many intracytoplasmic organellae and melanosomes.
In this case, we thought urinary cytological examination might be important before the operation, because the probe biopsy of malignant melanoma was contraindicative.
