Merkel cell carcinoma: update and review

Abstract

Merkel cell carcinoma (MCC) is a rare, aggressive, and often fatal cutaneous malignancy that is not usually suspected at the time of biopsy. Because of its increasing incidence and the discovery of a possible viral association, interest in MCC has escalated. Recent effort has broadened our breadth of knowledge regarding MCC and developed instruments to improve data collection and future study. This article provides an update on current thinking about the Merkel cell and MCC.

Figure 1

Primary MCC, chin.

Figure 2

Microscopic appearance of MCC. (A) H&E (original magnification, 200×) B. CK20 (original magnification, 200×).

Figure 3

Relative survival by extent of MCC. From Lemos et al.

Figure 4

Relative survival for MCC by stage at presentation in 2856 patients. Relative survival for MCC by stage at presentation in 2856 patients. Sufficient local, nodal, and distant data were available for stage classification of 2856 patients with MCC as summarized in Fig. 2. Cases presenting with local (A) or regional nodal/distant metastatic (B) disease are shown by substages with annual percent relative survival below each panel. Stages are as indicated directly on survival curves except for stage IIIA (microscopic node positive, clinical node negative), which could not be derived using National Cancer DataBase as described in the “Discussion” section. Curve IIIA* represents pathologically node-positive patients whose clinical node status was unknown (pN1, cNx). It is anticipated that patients at true stage IIIA with known clinically negative node status (pN1, cN0) may have better survival than line marked IIIA* (pN1, cNx). From Lemos et al.

Figure 5

LT antigen protein. LT, large T antigen; HS, heat shock; RB, retinoblastoma tumor suppressor protein.