Advances in Anatomic Pathology:
doi: 10.1097/01.pap.0000394993.82741.f9
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Calder, Kenneth B. MD*; Smoller, Bruce R. MD

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Departments of *Pathology

Pathology and Dermatology University of Arkansas for Medical Sciences Little Rock, AR

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In Reply:

In our review article “New insights into Merkel cell carcinoma” we focused on recent and clinically relevant updates pertaining to the pathogenesis and histologic evaluation of MCC. We appreciate the comment by Val-Bernal JF et al highlighting the phenomenon of regression in MCC in their study “Spontaneous Complete Regression in Merkel Cell Carcinoma after Biopsy”. Tumor regression has been noted in a variety of benign and malignant cutaneous neoplasms, and in some cases is a defining histologic feature. In the realm of dermatopathology lesions associated with regression include, keratoacanthomas, basal cell carcinomas, benign lichenoid keratoses, melanoma, and rare reports of MCC. As pathologists we often observe the various stages of regression in keratoacanthomas, while being much more judicious in the evaluation of features associated with complete regression as seen in basal cell carcinoma, lichenoid keratoses, or melanomas.

Focusing on MCC, there are numerous case reports in the literature describing regression of both primary and metastatic MCC. In our experience the clinical and histologic regression of MCC is rather rare. Before considering the incidence of regression in MCC, it would prove prudent to define the meaning of complete spontaneous regression. Earlier defined, spontaneous regression is the complete or partial disappearance of a tumor without earlier or concurrent external influences.1 In a review of the literature evaluating cases reported as “spontaneous regression” of MCC, there is a spectrum of lesions which were surgically incised/excised earlier,2 biopsied using a fine-needle technique,3 or excised with incomplete margins.4 On the basis of the stated definition of spontaneous regression, using the designation “spontaneous regression” in cases of MCC with regression is best avoided, as it does not fit the basic definition.

In melanoma there are specific microscopic features characteristic of regression noted at the initial histologic evaluation, hence representing spontaneous regression. Unlike melanoma, the majority of reported cases of MCC with regression are usually associated with earlier surgical intervention, implicating a role for the host immune response in regression. Regression is a rare feature of MCC, and its relevance with regard to Merkel cell polyoma virus, apoptosis, and clinical significance is yet to be elucidated.

Kenneth B. Calder MD

Departments of *Pathology

Bruce R. Smoller MD

†Pathology and Dermatology University of Arkansas for Medical Sciences Little Rock, AR

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1. Everson TC, Cole WH Spontaneous Regression of Malignant Melanoma. Spontaneous Regression of Cancer: A Study and Abstract of Reports in the World Medical Literature and of Personal Communications Concerning Spontaneous Regression of Malignant Disease, Chapter 4. 1966 Philadelphia WB Saunders Co:164

2. Ciudad C, Aviles JA, Alfageme F, et al. Spontaneous regression in Merkel cell carcinoma: report of two cases with a description of dermascopic features and review of the literature Dermatol Surg.. 2010;36:687–693

3. Turk T, Orlic ZC, Smoljan I, et al. Spontaneous regression of Merkel cell carcinoma in a patient with chronic lymphocytic leukemia: a case report J Med Case Reports.. 2009;3:7270

4. Kubo H, Matsushita S, Fukushige T, et al. Spontaneous regression of recurrent and metastatic Merkel cell carcinoma J Dermatol.. 2007;34:773–777

© 2011 by Lippincott Williams & Wilkins.


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