Diagnosis: Giant molluscum contagiosum
Molluscum contagiosum (MC) is a relatively common, benign, viral cutaneous infection that primarily affects children, sexually active adults, and immunodeficient individuals. MC accounts for approximately 1% of all diagnosed skin disorders in the United States; internationally, however, the incidence is higher.1 The causative organism of MC is a member of the Poxviridae family2 and is thought to be transmitted by close personal contact, autoinoculation, and fomites.3
MC is clinically characterized by the presence of pearly white, dome-shaped papules or nodules with central dells. The lesions are typically located on the trunk, body folds, extremities, and genitalia (particularly when the infection is sexually acquired).2,3 Pruritus and an eczematous reaction can develop around the lesions.
MC is a recognized ocular complication of acquired immune deficiency syndrome (AIDS). Periocular MC can also occur after eyebrow shaping in beauty salons.4 In human immunodeficiency virus (HIV)-positive patients, lesions are usually widespread, tend to be large, and usually occur during the advanced stage of HIV infection.2,5
The differential includes carcinoma
When considering a diagnosis of MC, you’ll need to rule out the following causes of similar-looking papules and nodules:
Nodular basal cell carcinoma presents as a slow-growing, firm, shiny, pearly nodule with fine telangiectasia. It may also present as a cystic lesion that can be mistaken for inclusion cysts of the eyelid. If left untreated, the tumor may ulcerate.
Juvenile xanthogranulomas are rubbery, tan-orange papules or nodules. Patients may have one or several papules or nodules in the head and neck region; these lesions may appear elsewhere, as well.
Cryptococcosis may present as painless papules or pustules, which then become nodules that may ulcerate. The lesions may show central umbilications.
Keratoacanthoma begins as a firm, roundish, skin-colored or reddish papule that rapidly progresses to a dome-shaped nodule, with a smooth, shiny surface and a central crateriform ulceration or keratin plug. Patients typically have a solitary lesion that may appear on the face, neck, or dorsum of the upper extremities.
Penicillosis often presents with MC-like skin lesions, in addition to fever, anemia, hepatomegaly, lymphadenopathy, and productive cough.
History and lab work clinch the Dx
Diagnosis is made by the distinctive clinical appearance, but can be confirmed by skin biopsy demonstrating eosinophilic molluscum bodies packed into the cells of the spinous layer of the epidermis.3 Giemsa stain of the material obtained from a crushed papule will reveal the presence of pathognomonic “molluscum bodies” in the cells of the epidermis.2,3
Our patient’s Giemsa stain revealed molluscum bodies. And since it is always wise to rule out concomitant HIV infection in patients who have giant MC, we tested our patient. Her results were positive; she had a CD4+ count of 93 cells/mm3.