Pediatric Dermatology Consult

An adolescent male presents with an eroded bump on the temple

Publish date: November 11, 2022

A 16-year-old male with a history of recurrent metastatic rhabdoid tumor of the kidney and pulmonary metastatic disease, currently being treated with nivolumab, pazopanib, topotecan, as well as a recent history of radiation therapy, presents to clinic for a nontender bump on the right temple. The lesion first appeared 3 months ago as a white-colored papule with surrounding erythema (photo A), which then spontaneously scabbed and bled over the last 2 weeks. Examination reveals a white colored papule with surrounding erythema and central hemorrhagic crusting on the right temple (photo B). Patient denies a history of other similar lesions. No other concerning skin lesions were found on skin exam.

The correct answer is (D), molluscum contagiosum. Upon surgical excision, the pathology indicated the lesion was consistent with molluscum contagiosum.

Molluscum contagiosum is a benign skin disorder caused by a pox virus and is frequently seen in children. This disease is transmitted primarily through direct skin contact with an infected individual.¹ Contaminated fomites have been suggested as another source of infection.² The typical lesion appears dome-shaped, round, and pinkish-purple in color.¹ The incubation period ranges from 2 weeks to 6 months and is typically self-limited in immunocompetent hosts; however, in immunocompromised persons, molluscum contagiosum lesions may present atypically such that they are larger in size and/or resemble malignancies, such as basal cell carcinoma or keratoacanthoma (for single lesions), or other infectious diseases, such as cryptococcosis and histoplasmosis (for more numerous lesions).^{3,4 A} giant atypical molluscum contagiosum is rarely seen in healthy individuals.

What’s on the differential?

The recent episode of bleeding raises concern for other neoplastic processes of the skin including squamous cell carcinoma or basal cell carcinoma as well as cutaneous metastatic rhabdoid tumor, given the patient’s history.

Leal Moyal

Eruptive keratoacanthomas are also reported in patients taking nivolumab, an anti-PD-1 immunotherapy, which the patient has received for treatment of his recurrent metastatic rhabdoid tumor.⁵ More common entities such as a pyogenic granuloma or verruca are also included on the differential. The initial presentation of the lesion, however, is more consistent with the pearly umbilicated papules associated with molluscum contagiosum.

Comments from Dr. Eichenfield

This is a very hard diagnosis to make with the clinical findings and history.

Dr. Lawrence F. Eichenfield

Molluscum contagiosum infections are common, but with this patient’s medical history, biopsy and excision with pathologic examination was an appropriate approach to make a certain diagnosis.

Ms. Moyal is a research associate in the division of pediatric and adolescent dermatology at the University of California, San Diego, and Rady Children’s Hospital, San Diego. Dr. Eichenfield is vice chair of the department of dermatology and professor of dermatology and pediatrics at the University of California, San Diego, and Rady Children’s Hospital, San Diego.