American Journal of Dermatopathology:
Letter to the Editor
Division of Dermatopathology, Department of Dermatology, University of Connecticut Health Center, Farmington, CT.
To the Editor:
The coexistence of molluscum contagiosum virus (MCV) infection in an epidermal inclusion cyst is rarely described. We report 2 additional cases of MCV infection in benign cutaneous epithelial cystic lesions with different histopathologic features. The possible different pathogenesis of these cystic skin lesions with regard to MCV infection is discussed.
Case 1 is a 51-year-old woman presented to her dermatologist with a flesh-colored papule (approximately 0.7 cm in diameter) on her left upper posterior thigh. A small central ostium was noted. The lesion was present for approximately 2 months but was asymptomatic. The patient had no known history or evidence at presentation of MCV lesions on the skin surface. The preliminary clinical diagnosis was of an epidermal inclusion cyst (EIC). A shave excision of the lesion was performed. The specimen was routinely formalin fixed, paraffin embedded and entirely sectioned with 5-μM sections stained with hematoxylin and eosin (H+E) for histopathologic review. H+E-stained sections revealed a small unilocular cyst with scattered foci of eosinophilic inclusion bodies within the cyst wall, consistent with MCV cytopathic changes. The intervening cyst wall showed an intact granular layer with overlying cornified cells in a laminated and basket weave pattern (Fig. 1).
Case 2 is a 32-year-old man presented to his dermatologist with a flesh-colored nodule (approximately 1 cm in diameter) on his left chest. A central ostium was noted. The lesion was present for approximately 3 months but was asymptomatic. The patient had no known history or evidence at presentation of MCV lesions on the skin surface. The preliminary clinical diagnosis was of an infected EIC. An excision of the site was performed. The specimen was routinely formalin fixed, paraffin embedded and entirely sectioned with 5-μM sections stained with H+E for histopathologic review. H+E-stained sections revealed a large multiloculated cyst with close approximation of the adjacent cystic components and eosinophilic inclusion bodies, consistent with MCV cytopathic changes, throughout the entire cyst wall (Fig. 2).
The coexistence of MCV infection in an EIC is an unusual presentation.1-9 A number of hypotheses have been proposed to describe the pathogenesis of these changes, including (1) coinoculation of MCV at the time of development of the EIC or (2) the invasion of MCV into a preexisting EIC.1-4 A chronological relationship and existence of portions of noninfected EIC wall has been put forward as evidence of the latter hypothesis in certain studies.5,6 In some cases, it has been postulated that MCV infection may play a direct role in the development of the EIC.1 The likely pathogenesis of the lesion in patient 1 is consistent with the second hypothesis because of the presence of a small unilocular cyst demonstrating only focal microscopic evidence of MCV infection in the cyst wall. However, we believe that the histologic features of patient 2 suggest that another hypothesis for the development of this type of lesion should to be considered. This second case demonstrated not only changes of MCV infection through the entire lesion but also multiloculated changes with close approximation of the adjacent cystic components. These latter features are not typical of an EIC. In addition, common variety superficial MCV lesions can demonstrate some degree of multilocularity. Therefore, downward extension and cystic change in a preexisting superficial MCV lesion in patient 2 is a possibility. As in our cases, most epidermal cysts demonstrate a small ostium opening to the skin surface, which could potentially communicate both MCV from the neighboring skin into the EIC and facilitate extension of MCV from an infected EIC to the adjacent skin. A number of reports describe the coexistence of typical MCV lesions in the same patient,1,3,6-8 and superficial MCV lesions on the skin have subsequently appeared adjacent to a site of an MCV-infected EIC.6,7 However, both our patients had no known history or evidence at presentation of MCV lesions on the skin surface and have not subsequently developed typical superficial MCV lesions.
Two patients with changes of MCV infection in benign cutaneous epithelial cystic lesions are described. The possibility that the lesion in each patient arose through different pathogenetic mechanisms is discussed. MCV infection may play a role in the development of some of the rare benign cutaneous epithelial cystic lesions, in which the cytopathic features of this virus are identified.
Amanda Phelps, BS
Michael Murphy, MD
Zendee Elaba, MD
Diane Hoss, MD
Division of Dermatopathology, Department of Dermatology, University of Connecticut Health Center, Farmington, CT
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