Diagnosis of Atypical Molluscum Contagiosum: The Utility of a Squash Preparation

Abstract

A 4-year-old boy was referred to the outpatient dermatology clinic for two growths on his scalp. The first lesion had been present on the vertex scalp for six months and was asymptomatic except for recent inflammation and drainage of white exudate. A second growth developed on the patient’s posterior parietal scalp in recent weeks and reportedly resembled the original appearance of the initial lesion. Review of systems was negative, and the parents denied any affected close contacts. There had been no intervention to the lesions. On examination, the vertex of the scalp revealed a 0.3 cm hemorrhagic crusted papule with surrounding desquamation and minimal surrounding erythema. The left posterior parietal scalp had a 0.2 cm smooth pearly papule. The remainder of the examination was unremarkable. The skin overlying the parietal scalp lesion was incised using a 19-gauge needle. A white, cheesy central core was removed with a comedone extractor (figure 1A▶). The specimen was then squashed with firm pressure between two glass microscope slides (figure 1B▶). The top slide was discarded, and the material on the bottom slide was stained with 3 ml of Giemsa stain (figure 1C▶). The slide was then gently rinsed with tap water. A single drop of mineral oil was applied to the air-dried specimen, followed by placement of a coverslip over the specimen. The slide was then viewed with light microscopy (figure 2▶). Cytologic examination revealed uniform, discrete and clustered purple ovals consistent with the large cytoplasmic viral inclusions of Molluscipoxvirus (Henderson-Paterson bodies), thus confirming the diagnosis of molluscum contagiosum (MC). As this was the only intact lesion on the full body exam of the child, the removal and squash preparation of the lesion’s contents was not only diagnostic, but therapeutic as well. No further treatment was required. Figure 1: (A) After incision with a 19-gauge needle, a comedone extractor is used to express the molluscum cheesy core. (B) The molluscum core is squashed between two glass microscope slides. (C) The squashed molluscum core is stained using 5 to 7 drops of Giemsa ... Figure 2: Discrete and clustered purple ovals consistent with large cytoplasmic viral inclusions of Molluscipoxvirus (Henderson-Paterson bodies), magnification x20. Inset: Magnified view of Henderson-Paterson body (arrow).