Criteria for the diagnosis of primary endocrine carcinoma of the skin (merkel cell carcinoma). A histological, immunohistochemical and ultrastructural study of 13 cases

Merkel Cells, Normal and Neoplastic: An Update

“…Merkel Cells, Normal and Neoplastic urothelium, Merkel cells, and MCCs [19,[28][29][30][31][32]. CK20 positivity ( Figure 8) and TTF-1 negativity help distinguish MCC from metastatic pulmonary small cell carcinoma [33].…”

Cytomorphologic Features of Merkel Cell Carcinoma in Fine Needle Aspiration Biopsies

“…15 Others, including Toker, have demonstrated eccrine and squamous differentiation within Merkel cell tumors, while still others have described focal areas of pleomorphism within their series of otherwise typical MCC. 5,13,17,24,30 Heenan et al described the presence of an occasional tumor cell with giant nuclei; Szadowska et al noted some tumor cells with pleomorphic or multilobated nuclei. 9,28 Finally, Leong et al described an MCC exhibiting squamous differentiation that was composed primarily of large, pleomorphic cells with strikingly irregular, pleomorphic, occasionally lobated nuclei.…”

“…29 Because of its usual morphology, the tumor is classically categorized as a "small blue cell" neoplasm. In recent years, however, it has become evident that MCC may manifest a much broader range of histologic features, including varying degrees of cellular pleomorphism, 9,16,17,28 but this morphologic variability has not been reflected in the cytology literature. Fine needle aspiration biopsy (FNAB) of MCC typically produces highly cellular smears of loosely clustered and individual, monomorphic tumor cells with round to oval, regularly contoured nuclei with scant cytoplasm.…”

Merkel-Zell-Karzinom des Handrückens

“…In seltenen Fällen tritt es auch am Stamm auf, hier zeigt es morphologisch häufig eine plaqueartige Effloreszenz. Histologisch sind monomorphe Zellen mit typischem Chromatinmuster auffäl-lig [3], die sich in der retikulären Dermis und Subkutis ausbreiten. Nicht betroffen sind die Epidermis, papilläre Dermis und Adnexen.…”