Spontaneous regression of Merkel cell carcinoma in a patient with chronic lymphocytic leukemia: a case report

Abstract

IntroductionMerkel cell carcinoma is a rare and aggressive primary cutaneous neuroendocrine malignant tumor. The tumor has a high rate of local recurrence after surgical removal. Spontaneous regression appears to be relatively common in this rare type of tumor.Case presentationWe describe the clinical course, cytological and histological findings of a Merkel cell carcinoma in a 70-year-old Caucasian woman, simultaneously diagnosed with chronic lymphatic leukemia. The tumor showed clinical regression after fine needle aspiration. At primary presentation, the tumor had no apparent leukocyte infiltration, but was completely cleared by T-cell mediated immunity within 3 weeks after fine needle aspiration.ConclusionFine needle aspiration may have acted as a mechanical trigger involved in the activation of cell-mediated immunity, leading to the clinical and histological regression of the tumor. To the best of our knowledge, this is the first case report of spontaneous regression of Merkel cell carcinoma in a patient with a co-malignancy, that is to say, chronic lymphocytic leukemia.

Tumor Infiltrating Immune Cells and Outcome of Merkel Cell Carcinoma: A Population-Based Study

“…Taken together, these findings suggest that tumor infiltrating lymphocytes might reduce the rate of metastasis more than the rate of tumor cell proliferation. The immune response may sometimes greatly influence progression of MCC, as several case reports describe MCCs that regressed spontaneously probably due to a local inflammation reaction in the tumor (21)(22)(23)(24)(25)(26). Yet, such responses are not robust enough in most cases to prevent tumor growth.…”

“…MCC may rarely (<2%) regress spontaneously or following mechanical or chemical irritation, suggesting a potential therapeutic role for the immune system modulating approaches (21)(22)(23)(24)(25)(26). Presence of lymphocytic infiltration (27,28) …”

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

“…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 .…”

“…Other cases of regression of MCC deviated from the standard in different ways. In one instance a diagnosis of chronic lymphocytic leukemia was diagnosed simultaneously with an MCC on the forearm of a 70‐year‐old man . The tumor regressed spontaneously 3 weeks after a diagnostic fine needle aspirate.…”

Cytological and Immunocytochemical Features of Merkel Cell Carcinoma on Fine Needle Cytology Samples: A Study of 22 Cases

“…Although MCC is an aggressive neoplasm, spontaneous regression has been also reported, even noted after fine needle cytology (FNC) performance, without any treatment [4][5][6][7]. It is still unclear how a mechanical stimulus, like FNC, can be a trigger for activating the immune system toward macrophagemediated digestion of malignant cells.…”