Diagnosis of atypical molluscum contagiosum: the utility of a squash preparation.

Molluscum contagiosum (MC) is a self-limited epidermal infection caused by the Molluscipoxvirus. It accounts for approximately 1% of all dermatologic diagnoses. The virus can be transmitted by infected fomites, casual or sexual contact, and self-inoculation, with a predilection for children, sexually active, or immunocompromised individuals. Molluscum lesions can affect any region of the body and typically present as asymptomatic 1mm to 5 mm pearly, white or skin-colored round papules with an umbilicated center. Morphologic variants of MC are common and include giant lesions greater than 5 mm, eczematous lesions, and folliculocentric lesions with secondary abscess formation. These less common presentations can closely mimic other dermatologic conditions, including lymphangioma, condyloma acuminatum, and basal cell carcinoma. Diagnosis of MC is typically made by clinical evaluation; however, atypical presentations pose a diagnostic challenge. An in-office diagnostic technique to definitively identify MC would be useful. We present the case of a 4-year old boy with an atypical presentation of molluscum contagiosum on the scalp and describe the diagnostic utility of the squash preparation technique to make the definitive diagnosis.