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Enlarging, annular rash on a 3-year-old girl
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A 3-year-old girl presents with concern for a rash on her right hip. Her mother first noticed it 7 months ago, stating that it started as a small, flaky, round spot that persisted and enlarged over the following month. She took her daughter to the pediatrician and was given a 3-week course of oral fluconazole without improvement.
Image: Coughlin CC
The mother then tried to treat the area with 1% hydrocortisone cream. Her daughter scratches at her hip occasionally, but does not complain of pain. The area continued to worsen, so she has brought her daughter to see you. The family lives in the northeastern United States and has not traveled in the past year. They have an 11-month-old cat, the patient attends day care, and her brother attends elementary school.
Upon examination, you note a large (> 10 cm) annular patch with excoriated papules at the outer half of the ring and relative central clearing. There is associated hyper- and hypopigmentation.
Case discussion
Diagnosis: (A) Tinea incognito (with Majocchi’s granuloma)
Tinea incognito is a term reserved for cutaneous dermatophyte infections that have been treated with topical steroids. Dermatophytes invade keratinized tissue and typically create scaly, annular patches on the skin.
Topical steroids change the appearance of the rash by altering the skin’s inflammatory response to the dermatophyte. In addition, steroids allow for a more permissive environment and can lead to proliferation of dermatophyte infections. When the dermatophyte penetrates deeper in the skin (such as via hair follicles), pustules and nodules can result; this is termed Majocchi’s granuloma.
The differential diagnosis includes contact dermatitis given the focal location. However, the patient should have more pruritus and fewer changes due to the topical steroid; 1% hydrocortisone is not potent enough to modify most cases of contact dermatitis. A cutaneous fungal (nondermatophyte) infection could be considered. However, without a history of immunosupression, trauma, or exposure, this is unlikely.
Chronic cutaneous lupus could be considered with the annular configuration and dyspigmentation; however, the lesion is hypopigmented in areas of excoriation and not truly scarring, making discoid lupus less likely. The appearance would be atypical for subacute cutaneous lupus, which is often annular but has a more psoriasiform morphology.
It is important to query families about their environment and contacts to adequately treat tinea infections and attempt to prevent recurrence. The most common causes of tinea corporis are Microsporum canis, Trichophyton tonsurans and T. rubrum. Family members could have any of these. If dermatophyte screen (or fungal culture) grew M. canis, the family’s cat should be examined by a veterinarian. Some people are asymptomatic carriers, so family members may appear unaffected but still be the source. Linens and clothes should be washed regularly in hot water to limit spread via fomites, as well.
In this case, the initial rash likely could have been treated with a topical azole antifungal (effective at treating small- to medium-sized lesions of tinea corporis). The papular component that developed indicates the presence of Majocchi’s granuloma, or deeper cutaneous infection — as hair follicles were considered the entry point — which requires oral therapy. This disease progression is akin to pustules seen in tinea capitis infections, which also typically require oral antifungal therapy to penetrate the hair shaft. Agents normally used to treat this infection include terbinafine, griseofulvin or itraconazole.
Tinea corporis typically presents as annular or nummular, scaly patches on the body. When treated with topical steroids, the appearance becomes atypical and is referred to as tinea incognito. Affected areas are less scaly and less inflammatory than untreated lesions. When a papular component is seen, Majocchi’s granuloma should be considered, as this change typically indicates the need for oral therapy to clear the infection. Practitioners should be aware of the different clinical presentations of tinea corporis in order to recognize variants and target therapies appropriately.
- References:
- Ive FA, et al. Brit Med J. 1968;doi:10.1136/bmj.3.5611.149.
- Jacobs JA, et al. Clin Infect Dis. 2001;doi:10.1086/338023.
- McGinness J, et al. Cutis. 2006;77:293-296.
- For more information:
- Carrie C. Coughlin, MD, recently completed a pediatric dermatology fellowship at The Children’s Hospital of Philadelphia and is joining the faculty at Washington University in St. Louis, Missouri. She can be reached at coughlincc@gmail.com.
- Marissa J. Perman, MD, is an attending physician at The Children’s Hospital of Philadelphia.
Disclosure: Coughlin and Perman report no relevant financial disclosures.