Merkel cell carcinoma in organ‐transplant recipients: report of two cases with unusual histological features and literature review

Abstract

In the setting of organ transplantation, Merkel cell carcinoma is much rarer than other non melanoma skin cancers but may show unusual histologic features. HPV do not seem to be involved in its pathogenesis.

Detection of a novel truncating Merkel cell polyomavirus large T antigen deletion in chronic lymphocytic leukemia cells

“…1,7 MCC is a rare and aggressive malignant neuroendocrine skin cancer of elderly and immunosuppressed patients. 8,9 However, MCC patients are at a 30-fold increased risk to develop chronic lymphocytic leukemia (CLL) that as MCC primarily affects elderly patients. [10][11][12] CLL is the most common leukemia in the Western world and is characterized by the accumulation of monoclonal mature B cells aberrantly expressing CD5.…”

Epidermotropic pagetoid spread and squamous cell carcinoma in situ in the overlying epidermis of Merkel cell carcinoma

“…Cases of MCC showing both pagetoid epidermal involvement and bowenoid changes were rare [6,7]. A similar case was recently reported in an organ-transplant recipient [7]. Although our case was not immunosuppressed, intraepidermal MCC tumor nests were intermingled with bowenoid changes in the overlying epidermis, and the bowenoid changes were also found in the border epidermis.…”

“…MCC is often associated with squamous differentiation, and overlying epidermis showing SCC in situ and invasive SCC have been reported in approximately more or less 10%. Cases of MCC showing both pagetoid epidermal involvement and bowenoid changes were rare [6,7]. A similar case was recently reported in an organ-transplant recipient [7].…”

Carcinome à cellules de Merkel

“…Cette tumeur semble favorisée par les rayons ultraviolets (UV), comme le suggère sa prédominance sur des zones photoexposées, l'association à d'autres cancers kératinocytaires cutanés (dont l'induction par les UV est bien documentée), l'apparition après PUVAthérapie 1 , l'incidence élevée au sein d'une même ethnie sur les zones à plus fort ensoleillement [3], ainsi que l'existence d'anomalies génétiques partagées avec les carcinomes spinocellulaires, comme les mutations induites par les rayons UVB sur les gènes p53 et H-ras [4]. Le déficit immunitaire semble constituer un facteur prédisposant important, comme en témoigne l'incidence élevée du CCM au cours d'états d'immunodépression iatrogène (traitements immunosuppresseurs pour des maladies auto-immunes ou allogreffes d'organe) [5] ou non-iatrogène (Sida, leucémies/lymphomes). Dans une série de 420 cas de CCM, 14,5 % des patients recevaient un traitement immunosuppresseur [6].…”