Merkel cell carcinoma is a rare, but highly malignant tumor of the skin with high rates of metastasis and poor survival. Its incidence rate rises and is currently about 0.6/100000/year. Clinical differential diagnoses include basal cell carcinoma, cyst, amelanotic melanoma, lymphoma and atypical fibroxanthoma. In this review article clinical, histopathological and immunhistochemical features of...

We report a case of malignant melanoma of Eustachian tube with extension to the middle ear cavity and nasopharynx in a 51-year-old woman who presented with right ear fullness. Computed tomography showed a soft tissue mass in the middle ear cavity and caused the widening and eroding of the bony eustachian tube. Magnetic resonance imaging showed well enhancing mass in eustachian tube extending na...

An 82-year-old man with Fitzpatrick skin type III presented for the evaluation of a lesion on the left upper back. A scaly pink papule was observed (Figure 1). The differential diagnosis included squamous cell carcinoma (SCC), actinic keratosis, basal cell carcinoma, and amelanotic melanoma. On dermoscopy, multiple coiled blood vessels (also termed glo-merular vessels) were scattered across the...

The K-1735 melanoma is a transplantable murine tumor which, when growing s.c., is composed of melanotic and amelanotic areas. Results from trocar transplantation studies of tumor fragments show that expression of this phenotypic diversity can be terminated within very few passages. In parallel experiments, passage of cell suspensions derived from the whole tumor maintains this heterogeneity of ...

Clinical and histologic studies were performed on 25 patients with malignant melanomas of the ciliary body and choroid. Portions of fresh tumor were quick frozen and processed by the histofluorometric technique to demonstrate the presence of biogenic amines. Separate portions of each tumor were fixed and processed for routine light microscopy. Specific fluorescence was visible in 21 of 23 pigme...