A Rare Case of Coexisting Pediculosis Capitis and Tinea Capitis in a Healthy Adult Female

Abstract

Pediculosis capitis is a common condition caused by infestation with the human head louse, Pediculus humanus capitis, and primarily affects children in the age-group of 6–12 years. The most prominent symptom is intense scalp itching, yet moving lice or nonmoving nits may be seen on the scalp and hair. Tinea capitis, also known as scalp ringworm, is a superficial fungal infection caused by keratinophilic fungi termed dermatophytes. Tinea capitis is rare in adults, and its symptoms include hair loss, dry scaly areas, redness, and itching. We here report a case of a rare coexistence between pediculosis capitis and tinea capitis in an otherwise healthy adult female, motivating the search for a possible cause of this rare coexistence and alarming dermatologists to be aware of the modified clinical appearance of this coexistence which could be mistaken with other conditions such as cutaneous lupus erythematosus or lichen planopilaris.

Established Facts

• Pediculosis capitis commonly affects school children and is usually presented by intense scalp itching.

• Tinea capitis in adults is almost always associated with chronic disorders, animal contact, and/or immunocompromised status.

Novel Insights

• We report a rare simultaneous coexistence of tinea capitis and pediculosis capitis in the same adult patient who is otherwise healthy and of high socioeconomic standard.

• The clinical presentation of this case morphologically mimics other dermatological conditions, which may lead to misdiagnosis and wrong treatment strategies.

• Dermatologists should be more aware of tinea capitis infection in the adult age-group as it is not only limited to immunocompromised patients but can also affect healthy individuals.

Introduction

Pediculosis capitis is a common infestation occurring in school-aged children and caused by the human head louse Pediculus humanus capitis. Head-to-head contact is the most common transmission route, but sharing clothing, pillows, or combs is another possible infestation method [1]. Tinea capitis is a fungal infection of the scalp involving both the skin and hair. It is a common condition seen primarily in the pediatric age-group and is far less common in adults [2].

Case Report

A 20-year-old female presented with itchy skin lesions affecting the scalp of 8 months duration. Physical examination showed multiple erythematous scaly patches of alopecia covered with scales and crusts. Whitish nodules firmly attached to hair shafts (nits) were also observed (Fig. 1a, b). Dermoscopy revealed the presence of a living louse sucking blood, confirming the diagnosis of pediculosis capitis (Fig. 1c; see online supplementary video). However, other notable dermoscopic findings of tinea capitis were observed, such as black dots, broken hairs, corkscrew, and comma hairs (Fig. 2a, b). Wood's light showed no fluorescence, while 10% potassium hydroxide examination of the scales scraping showed multiple branching hyphae (Fig. 2c).

Fig. 1.

a, b Multiple localized erythematous scaly areas of alopecia showing crusts and nits adhering to hair shafts. c Dermoscopic picture of a living louse while sucking blood from the host.

Fig. 2.

a, b Dermoscopic findings of tinea capitis: black dots (red arrow), short broken hairs (white arrow), corkscrew (green arrow), and comma hairs (blue arrow). c Multiple branching hyphae were observed in potassium hydroxide preparation (×100).

On general examination, there was neither lymphadenopathy nor affection of other body hair-bearing areas. There was no history of psoriasis, eczema, systemic diseases, or contact with animals or children. Laboratory workup was normal. Based on these findings, the diagnosis of combined infection of tinea capitis and pediculosis capitis was made. Treatment with ivermectin and griseofulvin ultramicrosize was started.

Discussion

Tinea capitis is rare in adults due to the protective fungistatic effect of sebum against dermatophyte infections. It may affect patients with the immunocompromised state due to existing malignancy, immunologic disorders, debilitating diseases, or being on immunosuppressive drugs. Postmenopausal women can also be infected due to hormonal changes altering the amount of sebum production [2].

Other predisposing factors in adults include animal contact, especially in rural areas. Clinically, tinea capitis in adults is often atypical and may mimic other diseases. Unless the possibility of dermatophyte infection is considered, the condition may go unnoticed, leading to inappropriate treatment. Trichophyton violaceum is the most common fungal pathogen in all dermatophytosis among Egyptian patients [2, 3].

Pediculus humanus capitis is an obligate exclusively human ectoparasite that lives on the scalp and feeds by sucking blood from the host and injecting saliva simultaneously. Itching caused by pediculosis occurs 4–6 weeks after the infestation onset because of the developed allergic reaction to lice saliva. Definitive diagnosis is by the detection of a living louse. In cases with heavy infestations, a secondary bacterial infection of the excoriated scalp may occur [1].

The coexistence of fungal infection with scalp pediculosis in the same patient is restricted to 2 case reports of white piedra occurring with pediculosis capitis [4, 5]. To our knowledge, this is the first reported coinfection of pediculosis capitis and tinea capitis in the same patient.

The body louse, Pediculus humanus humanus, is a well-established agent for transmitting pathogenic bacteria such as Rickettsia prowazekii, Bartonella quintana, and Borrelia recurrentis. Recently, pathogenic bacteria have been detected in head lice, but its role in transmitting pathogenic bacteria is not yet defined [6]. This way of transmission raises the question of whether itching induced by pediculosis is the predisposing factor for the infection with tinea capitis in our presented case, or whether the head lice are capable of harboring and transmitting fungal infection. Moreover, the moving lice could drag fungal spores and give this modified clinical picture.

The combined clinical, dermoscopic, and mycological features of this case are interesting due to the rarely simultaneous infection and infestation besides affection of a patient in the adult age-group in which tinea capitis is already rare. Therefore, a thorough examination of inflammatory scalp conditions using multiple diagnostic tools is required not only for the early recognition of such mimicking conditions that can be easily misdiagnosed but also for preventing the spread of infection and eliminating disfiguring hair loss.

Statement of Ethics

Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

The authors did not receive any funding.

Author Contributions

Both authors contributed equally to the design, drafting, intellectual content, final approval, and agreement of this work.

Supplementary Material

Video 1

Supplemental Video