TY - JOUR
T1 - Merkel cell tumor in a trichilemmal cyst
T2 - Collision or association?
AU - Ivan, Doina
AU - Bengana, Chafik
AU - Lazar, Alexander J.
AU - Diwan, A. Hafeez
AU - Prieto, Victor G.
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2007/4
Y1 - 2007/4
N2 - An 86-year-old white male presented with an erythematous, painless, slowly growing, and firm left thigh nodule. Histologic examination revealed a dermal proliferation of monomorphous cells arranged in trabeculae, nests, and sheets with an infiltrative growth pattern. The cells had a high nuclear-cytoplasmic ratio, finely granular nuclear chromatin, and nuclear molding. Numerous mitotic figures, apoptotic cells, and individual cell necrosis were present; lymphovascular invasion was identified. The tumor was attached, demonstrating pagetoid intraepithelial migration, to a follicular cyst lined by squamous epithelium, lacking a granular cell layer and filled with compact keratinous content, diagnostic of trichilemmal cyst. Immunohistochemical study revealed that tumor cells expressed pan-cytokeratin (CK), chromogranin, synaptophysin, neuron-specific enolase, and CK20 (dotlike staining pattern), thus supporting the diagnosis of Merkel cell carcinoma. The association of Merkel cell carcinoma with a cyst is an exceptionally rare occurrence. As a result of the prominent involvement of the cyst wall by tumor cells, we favor that in this case carcinoma arose in the trichilemmal cyst rather than being a collision tumor. This hypothesis is also supported by the recent observation that Merkel cells are frequently present within normal hair follicles, especially in the isthmic portion that corresponds with the area of origin of the trichilemmal cyst.
AB - An 86-year-old white male presented with an erythematous, painless, slowly growing, and firm left thigh nodule. Histologic examination revealed a dermal proliferation of monomorphous cells arranged in trabeculae, nests, and sheets with an infiltrative growth pattern. The cells had a high nuclear-cytoplasmic ratio, finely granular nuclear chromatin, and nuclear molding. Numerous mitotic figures, apoptotic cells, and individual cell necrosis were present; lymphovascular invasion was identified. The tumor was attached, demonstrating pagetoid intraepithelial migration, to a follicular cyst lined by squamous epithelium, lacking a granular cell layer and filled with compact keratinous content, diagnostic of trichilemmal cyst. Immunohistochemical study revealed that tumor cells expressed pan-cytokeratin (CK), chromogranin, synaptophysin, neuron-specific enolase, and CK20 (dotlike staining pattern), thus supporting the diagnosis of Merkel cell carcinoma. The association of Merkel cell carcinoma with a cyst is an exceptionally rare occurrence. As a result of the prominent involvement of the cyst wall by tumor cells, we favor that in this case carcinoma arose in the trichilemmal cyst rather than being a collision tumor. This hypothesis is also supported by the recent observation that Merkel cells are frequently present within normal hair follicles, especially in the isthmic portion that corresponds with the area of origin of the trichilemmal cyst.
KW - Bulge region
KW - Merkel cell carcinoma
KW - Trichilemmal cyst
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U2 - 10.1097/01.dad.0000246174.73447.73
DO - 10.1097/01.dad.0000246174.73447.73
M3 - Article
C2 - 17414443
AN - SCOPUS:34147149244
SN - 0193-1091
VL - 29
SP - 180
EP - 183
JO - American Journal of Dermatopathology
JF - American Journal of Dermatopathology
IS - 2
ER -