Unique Cyst in a 22-Year-Old Man

DISCUSSION Molluscum contagious (MC) is a cutaneous infection described by Baterman in 1817. The etiologic agent is a DNA poxvirus. MC has been associated with other lesions like melanocytic nevus and/or epidermoid cyst (EC). The first case of MC in an EC was reported by Hodge et al in 1973. They reported a 33-year-old healthy man with a unique single lesion in the right thigh. The clinical diagnosis was an EC. Histology showed a true EC with molluscum bodies in both the wall and cavity. The patient also had a typical MC lesion in the eyelid. They concluded that it occurred as an inoculation of the EC by molluscum viruses. Recently, a few more cases had have been reported, but there are still not many examples. All cases have occurred in healthy HIV-negative patients. The exact pathogenic mechanisms are uncertain. Aloi and Pippione in 1985 suggested 2 theories: the first, molluscum virus infects the follicular infundibulum during the formation process of the EC, and the second, molluscum viruses can invade the dermis and infect an already formed EC. Other authors agree with this explanation. Ive in 1985 thought that MC could induce the formation of EC when the virus was inoculated in the follicular infundibulum. Some authors postulate an increased immunoreactivity of the basal follicular keratinocytes in the presence of epidermic growth factor, which induces follicular hyperplasia and cyst formation. Chiu et al in 2010 concluded that satellite skin lesions are produced when the MC virus moves from the cyst to the epidermis through a follicular conduct. It is interesting that similar to other reported cases, our case lacked any MC lesions on the cutaneous surface. Additionally, we have seen skin biopsies of MC with pseudocyst formation. Some are due to epidermal invagination, whereas others are artifacts due to faulty specimen orientation leaving a portion of epidermis in the dermis. In addition, our case is interesting because, although there are several similar reports to date, the entity is still infrequent and there are none from our country. Also, it emphasizes that the clinical presentation in these cases is nonspecific and the definitive diagnosis is made through histopathologic analysis. Importantly, this case is unique in that the clinical lesion was not visible and was detected only by palpation. Most of the previous reports described visible nodular lesions.