Trichorrhexis Invaginata in Tinea Capitis: A Rare Occurence

An 8-year-old male presented with a large patch of alopecia over the scalp associated with itching for five months. On cutaneous examination, a solitary patch of alopecia of size 5 cm × 5 cm associated with erythema, purulent deposits, and yellowish-white scale-crust over the alopecic patch was present over the left parietotemporal scalp [Figure 1]. Trichoscopic examination by Dermlite DL4 with ×10 magnification under polarized mode revealed black dots, broken hairs, beaded hairs, golf-tee sign, yellow and white homogeneous areas on a pinkish background along with yellow-white scale-crusts [Figure 2]. Light microscopy under ×40 magnification of the plucked hair showed invagination of the distal hair shaft into the proximal hair shaft, suggestive of trichorrhexis invaginata [Figure 3]. The potassium hydroxide mount of the plucked hair revealed multiple thin, hyaline-branched septate hyphae within the hair shaft. Fungal culture of the hair shaft showed growth of Trichophyton verrucosum. The patient was started on oral micronized griseofulvin at a dose of 20 mg/kg for 1 month, after which there was significant improvement in the lesion.Figure 1: A solitary patch of alopecia of size 5 cm × 5 cm associated with erythema, purulent deposits, and yellowish-white scale-crust over the alopecic patch present over the left parieto-temporal scalpFigure 2: Trichoscopy by Dermlite DL4 with ×10 magnification under polarized mode revealed black dots, broken hairs, beaded hairs (red arrow), golf-tee sign (black arrow), yellow and white homogenous areas on a pinkish background along with yellow-white scale-crustsFigure 3: Light microscopy (×40 magnification) of the plucked hair showed invagination of distal hair shaft into the proximal hair shaftThe characteristic trichoscopic features diagnostic of tinea capitis include comma hairs, cork-screw hairs, morse-code-like hairs, zig-zag hairs, bent hairs, block hairs, and i-hairs.[1] Other trichoscopic findings include black dots, broken hairs, and perifollicular and interfollicular scaling.[1] Trichorrhexis invaginata (TI), or bamboo hair, has been described characteristically in Netherton syndrome (NS), although it can occur as isolated finding.[2,3] The trichoscopic features described in TI include multiple irregularly placed small nodules along the hair shaft, which show ball-in-cup appearance on high magnification.[4] Golf-tee sign demonstrates the presence of the proximal cupped end of TI after the fracture of the distal end.[4] Similar features have been found in the trichoscopy of the index case. Diagnosis of NS requires the presence of at least one hair shaft with TI.[4] This case highlights the presence of this rare hair shaft disorder in tinea capitis and adds to the etiology of TI. Declaration of patient consent The authors certify that they have obtained all appropriate consent forms, duly signed by the parent(s)/guardian(s) of the patient. In the form, the parent(s)/guardian(s) has/have given his/her/their consent for the images and other clinical information of their child to be reported in the journal. The parents understand that the names and initials of their child/children will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.