Spontaneous regression of Merkel cell carcinoma: A case report and review of the literature

Abstract

INTRODUCTIONMerkel cell carcinoma (MCC) is a rare and highly aggressive primary cutaneous neuroendocrine carcinoma, most often occurring in the elderly. Recurrence is frequent and in 40% of cases regional and distant metastases develop. Despite this, there have been reports of spontaneous regression. We report the first case of MCC with primary complete spontaneous regression of the nose in an 86-year-old woman following an incisional biopsy.PRESENTATION OF CASEAn 86-year-old woman presented with a violaceous lump on the left side of the nose measuring 25 × 25 mm. Incisional biopsy of the lesion showed MCC and immunohistochemistry confirmed diagnosis. Following an 8-week period the lesion completely disappeared and histology did not show any residual MCC but immunohistochemistry demonstrated a mixture of T and B cells.DISCUSSIONComplete spontaneous regression (CSR) is rare. The literature documents 22 similar cases of CSR of MCC. From this case report and previous literature the most likely reason for regression is a T-cell mediated immune response.CONCLUSIONTo the best of our knowledge, this is the first described case of MCC with primary CSR of the nose. Exact mechanism of regression remains unclear. Further research is needed in identifying pathway of immune response and possible immunotherapy as a cure.

Complete spontaneous regression of Merkel cell carcinoma (1986–2016): a 30 year perspective

“…It seems likely that they are colluding factors in the generation of an anti‐tumoral immune response. Although many reports of CSR of MCC were published since 2008 none of them documented the viral status of the tumor . As part of the re‐examination of our case, (discussed above), we determined that the tumor was MCPyV positive …”

“…Since the seminal report by O' Rourke and Bell in 1986, less than 40 cases of regression of MCC have been published in the North American, Japanese and European literature . Mid‐way through the ensuing 30 years, Connelly and colleagues conducted a helpful review of the topic .…”

“…In the years following Connelly's review additional reports and further helpful overviews of CSR of MCC were published . These cases mirrored the established clinical paradigm.…”

Rationale For Immune-Based Therapies in Merkel Polyomavirus-Positive and -Negative Merkel Cell Carcinomas

“…Additionally, MCCs can regress following withdrawal of immune suppressive treatment [35,36] and spontaneous regression of MCCs is associated with T cell and foamy macrophage infiltration suggesting that regression may be immune-cell mediated [37,38]. While rare, spontaneous regression in MCC is much more common (1.3 per 1000 cases) than in other malignancies (1 in 60,000-100,000 cases) [38].…”

“…While rare, spontaneous regression in MCC is much more common (1.3 per 1000 cases) than in other malignancies (1 in 60,000-100,000 cases) [38]. Furthermore, a subset of advanced stage MCC patients present with unknown primary tumors (no primary skin lesions are detectable) likely as the result of immune-mediated clearance of the primary lesion and these patients have markedly improved overall and disease-specific s urvival [39].…”