Spontaneous Regression in Merkel Cell (Neuroendocrine) Carcinoma of the Skin

Abstract

In two Japanese women, 68 and 88 years old, Merkel cell (neuroendocrine) carcinoma of the face developed. Their tumors regressed after biopsy was performed, a rare occurrence. Histological and electron microscopic examination showed apoptosis, cellular necrosis, and an infiltration composed mainly of lymphocytes in the tumors. These changes may have been related to the mechanism of regression. It is interesting that our two patients were women, as was another patient described with Merkel cell carcinoma regression, in light of the fact that the prognosis of this tumor is sex dependent.

The Role of the Immune Response in Merkel Cell Carcinoma

“…Studies of primary and metastatic MCC that were observed to regress have demonstrated infiltration by immune cells, including CD4 + , CD8 + , and CD3 + T cells and macrophages [47,48,49]. An examination of tumors that subsequently partially or completely regressed after biopsy found a significant increase in T cells compared to tumors that did not regress [50].…”

Spontaneous regression in primary cutaneous neuroendocrine (Merkel cell) carcinoma: a rare immune phenomenon?

“…Merkel cell carcinoma (MCC) is a rare malignant highly aggressive tumour arising from neuroendocrine cells 1 . Despite the aggressive course of MCC, 11 previous cases of regression in MCC have been reported in the English literature and four additional cases are only available in Japanese 2–9 …”

“…The estimated prevalence of spontaneous regression when considering all neoplastic disease has been reported as less than one case of regression in 60 000–100 000 neoplasms 10 . In a review of the English literature we have found 11 previously reported cases of partial/complete regression of MCC, three of them with nodal metastasis that also regressed 2–9 . In most cases regression of the primary tumour was preceded by a biopsy of the lesion; a procedure that may stimulate the immune system against neoplastic disease.…”

Neuroendocrine carcinoma of the skin with a lymphoepithelioma-like histological pattern

“…Over recent years, eight patients (five women and three men) with spontaneously regressing NCS have been reported; 3–9 in six of these, regression was related to cell‐mediated immunity, due to an abundant population of cytotoxic T lymphocytes (CD3+ , CD8+), and in four cases it was associated with a more favourable clinical course 4–7 . However, the patient reported by Rosso et al 1 .…”