Dermoscopic image of the hairs in a very early lesion of tinea capitis caused by Trichophyton rubrum

Key Clinical Message

While the initial lesions of tinea capitis are often overlooked due to their small size and numerous hairs emerging from the follicle, it is crucial not to dismiss the partial presence of comma or harpin hairs and black spots.

1. CASE PRESENTATION

A 57‐year‐old man with a history of stroke and severe renal dysfunction due to diabetes visited our hospital after his wife noticed a patch of hair loss on the back of his head. An approximately 1 cm diameter area of alopecia was observed in the occipital region (Figure 1A,B). Dermoscopic examination revealed hair broken in various shapes (Figure 1C). Suspecting a fungal infection, a KOH microscopic examination was conducted on the desquamation of the affected scalp, but no fungus could be identified. The patient had no history of pet ownership nor involvement in martial arts. Despite this, the hair characteristics seen under dermoscopy strongly suggested a fungal infection.

FIGURE 1.

(A) An overall view of the occipital area was shown. From a distance, the area of hair loss is not visible. (B) When approaching, an area of alopecia was found. (C) Dermoscopic image of the epilation area. Black dots (blue arrows), comma hairs (green arrows), and hairpin hairs (yellow arrows) are observed in a small portion of the image.

Consequently, we cultured a sample of the broken hair for fungal growth. The culture medium yielded the development of two types of colonies (Figure 2A,B). DNA was extracted from the two types of colonies according to the QIAamp DNA Mini Kit® (Qiagen, German town, MD, USA) protocol, and PCR amplification of the ITS region of the fungus was performed. Sequencing of the PCR products identified Trichophyton rubrum (Accession number MT623559.1) in both colonies. The patient was instructed to apply Luliconazole cream to the epilation area from the first visit. The condition mildly improved by the second visit (7 days after the first visit). The patient was scheduled to switch to oral antifungal medication after a fungal culture showed a growing fungal colony; however, the patient did not return to our clinic thereafter.

FIGURE 2.

(A, B) Colonies of two different shapes developed by pulling hairs from the epilation area and culturing them on agar medium. Red arrows indicate white‐domed colonies. Blue arrows indicate white axle‐shaped colonies. “A” represents the front of the medium, and “B” represents the back of the medium.

Microsporum canis and Trichophyton tonsurans account for the majority of cases of tinea capitis, ¹ typically transmitted through animal care and human contact. Tinea capitis caused by T. rubrum is relatively rare, making it challenging to estimate from the patient's life history and is often discovered in severe cases. ² Consequently, initial lesions are not well‐documented, and the clinical picture is vague.

We have described the early characteristics of a tinea capitis area caused by T. rubrum. The patient, being diabetic, likely transmitted the infection from his tinea pedis site to his head. Fungus‐infected hairs are typically brittle and prone to shedding. However, in this early stage of T. rubrum infection, the hairs are stiff. A distinctive feature is the presence of black spots, hairpin, and comma hairs in the center of the area with numerous hairs. These are difficult to discern with the naked eye, necessitating dermoscopy. The initial lesions of tinea capitis may be challenging to detect through microscopic examination alone, and diagnosis may require cultivation. Tinea capitis is more common in patients predisposed to infection and, if untreated, can lead to extensive hair loss, complicating treatment.

Based on this case, we recommend careful evaluation of hair condition using dermatoscopy and not hastily diagnosing based on conditions like alopecia areata associated with autoimmune diseases or post‐viral alopecia. Accurate diagnosis is essential and requires dermatoscopy.

AUTHOR CONTRIBUTIONS

Makoto Kondo: Data curation; writing – original draft. Takehisa Nakanishi: Writing – review and editing. Koji Habe: Writing – review and editing. Keiichi Yamanaka: Project administration; writing – review and editing.

FUNDING INFORMATION

The authors did not receive any financial support for this study.

CONFLICT OF INTEREST STATEMENT

The authors declare no competing interests.

ETHICAL STATEMENT

Not applicable.

CONSENT

Written informed consent was obtained from the patient to publish this report in accordance with the journal's patient consent policy.

Kondo M, Nakanishi T, Habe K, Yamanaka K. Dermoscopic image of the hairs in a very early lesion of tinea capitis caused by Trichophyton rubrum . Clin Case Rep. 2024;12:e8706. doi: 10.1002/ccr3.8706

DATA AVAILABILITY STATEMENT

The datasets generated and analyzed will be available upon request to the corresponding author.