Kerion due to microsporum gypseum in a 1-month-old infant.

Microsporum gypseum is a rare cause of kerion in infancy. Light microscopy, fluorescent microscopy and fungal culture of the infected hair aids in early and correct diagnosis. Griseofulvin is the drug of choice for ectothrix fungi. We report a case of neonatal kerion caused by M. gypseum occurring at the age of 1 month, successfully treated with griseofulvin.

INTRODUCTION

Kerion is extremely rare in the neonatal period. In addition, kerion due to Microsporum gypseum has been reported only in older children. We describe a case due to M. gypseum that developed at 1 month of age.

CASE REPORT

A 3-month-old, otherwise healthy infant was brought with an inflamed plaque on the scalp, that had first developed when he was 1 month old. There was no history of any discomfort or pain. He had been treated with multiple courses of systemic antibiotics and a steroid-antibiotic cream topically, without response. The child had been referred to the Pediatric Surgery Department for a scalp biopsy and his parents had been advised a dermatology consultation before the procedure. His mother had a hyperpigmented annular plaque on the dorsum of the right hand, which was subsiding after application of terbinafine cream.

On examination, there was a round, tender, boggy plaque 7 cm in diameter on the vertex of the scalp, with almost total loss of hair, with multiple pin-head sized erosions and exudation of pus from some of the follicular orifices [Figure 1].

Figure 1

Erythematous plaque with hair loss on the infant's scalp and an annular, hyperpigmented plaque with central clearing on the mother's hand

Routine investigations were all within the normal limits. Wood's lamp examination of the scalp showed no fluorescence. Light microscopic examination of the scanty, easily pluckable hair on the plaque after addition of 30% potassium hydroxide (KOH), revealed small ectothrix spores. Fluorescent microscopy of the hair revealed accentuation of auto-fluorescence of the affected hair with destruction of the normal architecture of the cortex towards the hair root [Figure 2a–c].

Figure 2

(a and b) Small sized ectothrix spores in groups and chains (light microscopy ×40), (c) Accentuation of auto-fluorescence of the hair with destruction of the normal architecture of the cortex (fluorescent microscopy ×10)

Fungal culture in modified Sabouraud's dextrose agar medium showed brown colonies with white cottony centers, which were yellow on the reverse. Microscopic examination of the colony morphology with lactophenol cotton blue, revealed symmetrical, ellipsoidal, thin-walled, six-celled maroconidia with rounded ends [Figure 3a–c]. KOH examination and fungal culture from the mother's lesion were negative.

Figure 3

(a) Culture tubes showing colonies with white, cottony centers. (b) Colonies colored yellow on the reverse. (c) Culture stained with lactophenol cotton blue showing the characteristic macroconidia (light microscopy ×40)

A diagnosis of kerion due to M. gypseum was made. The patient was treated with ultra-micronized griseofulvin in a dose of 10 mg/kg body weight/day, in two divided doses. The lesion healed completely in 6 weeks with near complete regrowth of hair [Figure 4] and a repeat fungal culture of the hair was negative.

Figure 4

Healed lesion with regrowth of hair

DISCUSSION

Tinea capitis is common in children but rare in neonates.[1] In general, a history of a parent or grandparent with a dermatophyte infection as in our case, or indirect contact with pets, usually rabbits, is elicited.[1234]

The causative fungi are Microsporum and Trichophyton species. Around 15 species belonging to the Microsporum genus infect hair, producing tiny ectothrix microspores. M. gypseum is a ubiquitous geophilic fungus. It almost exclusively affects hair, and though a rare cause of tinea capitis, it is particularly prone to develop inflammatory lesions. It is non-fluorescent, as are most fungi infecting hair in South India.[5] The characteristic findings on direct microscopy, morphology of the colonies in culture and the fungal preparations stained with lactophenol, are diagnostic.

In adults, the hair is resistant to fungal invasion because of the fungistatic activity of short and medium chain fatty acids in the sebum. In the case of infants, the persistence of maternal hormones in the first few weeks of life is therefore likely to confer similiar resistance to some extent. The inflammation in kerion is probably due to a T-cell mediated hypersensitivity reaction to the dermatophyte.[2] This type of reaction is often minimal in neonates due to the immature immune system.

Kerion may be mistaken for impetigo, folliculitis, abscesses and carbuncles. Erythematous, annular lesions on the scalp in a 5-day-old baby has been misdiagnosed as neonatal lupus erythematosus.[3] Limited knowledge of this rare condition in neonates can lead to delayed diagnosis, resulting in considerable morbidity, including scarring alopecia. Another consequence of undiagnosed kerion is the possibility of unnecessary biopsies and potentially harmful surgical intervention in young infants.[67]

Our case is unusual, as very few cases of kerion in neonates have been reported, and those due to M. gypseum, only in older children. In addition, our purpose is to create awareness among non-dermatological physicians, of the diagnostic pitfalls and excellent outcome of prompt and appropriate treatment of this condition.