Multiple scabietic nodules on the scrotum in a patient living with HIV infection

Hidenori Nakagawa; Akiko Imanishi; Tomohiro Asaoka; Michinori Shirano

doi:10.3949/ccjm.92a.24121

A 21-year-old man presented to the outpatient clinic with multiple itchy nodules on his scrotum. He was sexually active with men and had a history of human immunodeficiency virus (HIV) infection.

Two months earlier, he was hospitalized for HIV-associated Pneumocystis jirovecii pneumonia and was treated with sulfamethoxazole-trimethoprim and glucocorticoids. At the time the patient was diagnosed with HIV infection and admitted to the hospital, his HIV viral load was 670,000 copies/mL and his CD4 T lymphocyte count was 63 cells/mm³. Therapy using the combination antiretroviral drug bictegravir/emtricitabine/tenofovir alafenamide was started immediately after he completed treatment for P jirovecii pneumonia.

Several weeks after the patient was discharged from the hospital, he presented with itching in both hands. He had no history of contact with animals and denied sexual intercourse after being discharged. At the time of the outpatient visit, his HIV viral load was 170 copies/mL and his CD4 T lymphocyte count was 220 cells/mm³.

On examination, several pruritic erythematous papules and nodules were observed on the scrotum (Figure 1). Small erythematous macules on both hands and linear keratotic burrows on the right volar wrist were also seen (Figure 2).

Figure 1

Itchy erythematous papules and nodules on the patient’s scrotum.

Figure 2

Linear keratotic burrow (arrow) on the right volar wrist.

Microscopic examination of scrapings from the scrotal nodules and keratotic lesions on the hands revealed Sarcoptes scabiei mite larvae and eggs (Figure 3), confirming the diagnosis of scabies.

Figure 3

Microscopic study (potassium hydroxide, magnification ×100) of scrapings from the scrotal nodules and keratotic lesions on the wrist revealed scabies mites (arrows) and eggs (arrowheads).

The patient received a single dose of oral ivermectin 0.2 mg/kg, followed by a second dose 1 week later. Following treatment, the itchy nodules on his scrotum gradually improved, and his symptoms disappeared completely after 2 weeks. It was unclear how he contracted scabies, as he lived alone; there was no one to examine or treat as a close contact of a scabies patient.

SCABIES

Scabies is a parasitic skin infection caused by S scabiei var hominis, which is transmitted by direct prolonged skin contact or sharing bedding or clothing.^1–3 The incubation time after the first exposure is between 3 and 6 weeks, while symptoms may appear as soon as 1 day after repeated exposures.²

Itching and skin lesions, including papules and nodules, in scabies occur due to a hypersensitivity reaction to the mite and its shed skin and feces.³ Common symptomatic sites include the wrists, hands, fingers, umbilicus, hips, axillae, intertriginous grooves, and feet. Scabies is diagnosed by microscopic examination of skin scrapings of affected sites using a potassium hydroxide preparation to identify mites, eggs, and fecal material.¹

Clinically characteristic signs of burrows—created when fertilized female mites tunnel into the epidermis to lay their eggs—can aid in the diagnosis (Figure 2).³ Burrows appear as snake-like, white or light brown, slightly raised lines several millimeters in length in the upper epidermis, and are typically located on the flexure surface of the wrist and elbows, creases of the palms and soles, genitalia, and axillae and between the fingers and toes.^1,3

When a patient presents with itchy scrotal nodules, scabies should be considered, and a sample of the skin scrapings from the lesions should be collected for microscopic examination. Other causes of nodular lesions of the scrotum include testicular or metastatic tumors, contact dermatitis, calcinosis, polyarteritis nodosa, and infectious diseases. Infectious diseases that cause nodular lesions include viral infections such as human papillomavirus, mycobacterial infections, and bacterial infections such as Staphylococcus aureus and Treponema pallidum.⁴

Oral ivermectin, administered in 2 doses 1 to 2 weeks apart, is one of the first-line treatments for scabies in adults who are not pregnant.^1,2 It is important for the patient to take a second dose because ivermectin is not effective against the eggs of the scabies mite.

DISCLOSURES

The authors report no relevant financial relationships which, in the context of their contributions, could be perceived as a potential conflict of interest.

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