Abstract
Crusted scabies is a severe, highly contagious variant of scabies that predominantly affects immunocompromised individuals. Although it usually involves extensive areas of the body, isolated scalp involvement in adults is exceedingly rare. This report describes a case of crusted scabies confined to the scalp in a 63-year-old male liver transplant recipient receiving everolimus therapy. The case emphasizes the importance of considering atypical presentations of scabies in immunosuppressed patients and highlights the diagnostic value of dermoscopy in challenging clinical scenarios.
INTRODUCTION
Crusted scabies, also known as Norwegian scabies, is a rare but severe infestation caused by Sarcoptes scabiei var. hominis. It is characterized by hyperkeratotic, crusted plaques that contain numerous mites and is most commonly observed in individuals with impaired immune function, including organ transplant recipients and patients receiving immunosuppressive therapy.1
Scalp-only involvement in adults is extremely uncommon and may mimic inflammatory scalp disorders such as seborrheic dermatitis or psoriasis.2 This report presents a rare case of crusted scabies confined to the scalp in a liver transplant recipient undergoing everolimus therapy.
CASE REPORT
A 63-year-old male who had undergone liver transplantation one year prior presented to the dermatology clinic with persistent pruritus and scaling of the scalp. His post-transplant treatment regimen included everolimus 0.25 mg twice daily and ursodeoxycholic acid 250 mg once daily. His medical history was notable for diabetes mellitus and benign prostatic hyperplasia.
Two years before the current presentation, the patient had been diagnosed with classic scabies and had been treated with six courses of permethrin cream. Although generalized pruritus and body lesions resolved after treatment, scalp itching persisted. The patient sought medical evaluation multiple times and was diagnosed with seborrheic dermatitis; topical corticosteroid lotion was prescribed without clinical improvement (Figure 1a, b).
Dermatological examination revealed diffuse erythema with localized, fine, compact scaling on the scalp. Dermoscopic evaluation demonstrated the characteristic “delta wing jet” sign suggestive of Sarcoptes scabiei infestation (Figure 2). Microscopic examination of scalp scrapings revealed more than ten live mites and numerous eggs in a single field, confirming the diagnosis of localized crusted scabies.
Treatment was initiated with permethrin cream applied for three consecutive days and was repeated one week later. Following therapy, complete resolution of lesions was achieved and pruritus subsided (Figure 3a, b).
DISCUSSION
Crusted scabies is a severe form of scabies characterized by a high parasite burden and extensive hyperkeratotic lesions. It most frequently occurs in individuals with significant immunosuppression, including patients with human immunodeficiency virus infection, patients with malignancies, patients with autoimmune diseases, or organ transplant recipients.2 While classic scabies typically involves interdigital spaces, wrists, and the trunk, crusted scabies may present with atypical locations, which may lead to delayed diagnosis.
Although scalp involvement is uncommon in classic scabies, crusted scabies affecting the scalp has been reported in immunosuppressed patients. In a patient with systemic lupus erythematosus, an occipital plaque initially misdiagnosed as psoriasis was later confirmed as crusted scabies by biopsy.3 Similarly, dermatomyositis patients receiving immunosuppressive therapy have been reported to develop crusted lesions involving the scalp and face.4 In an adult T-cell leukemia patient positive for human T-lymphotropic virus type 1, scalp and auricular crusted lesions were initially attributed to leukemia-related skin manifestations.5 Additionally, pediatric patients with scalp involvement have been misdiagnosed as tinea capitis prior to microscopic confirmation of scabies.6
CONCLUSION
The present case represents a rare instance of crusted scabies confined to the scalp in an adult liver transplant recipient. Persistent, treatment-resistant scalp pruritus in immunosuppressed individuals should prompt consideration of scabies in the differential diagnosis. Dermoscopy and microscopic examination are essential tools for early and accurate diagnosis. In such patients, inclusion of the scalp in topical treatment regimens may help prevent persistent infestation and relapse.
