Pembrolizumab-Induced Lichen Planus on the Scalp of a Patient with Non-Small-Cell Lung Carcinoma

A 67-year-old man with non-small-cell lung carcinoma was referred to our department because of a pruritic rash on his head and upper extremities. Prior to the development of the rash, he had received 4 cycles of combination therapy with pemetrexed, carboplatin, and pembrolizumab, followed by 2 cycles of pembrolizumab monotherapy. On physical examination, violaceous scaly erythema grouped on his scalp and upper extremities. Histologically, the scalp lesions demonstrated irregular acanthosis that formed a characteristic saw-tooth appearance with hypergranulosis and typical lichenoid tissue reaction. These findings suggested that the scalp lesions were lichen planus. Two-week administration of topical corticosteroid dramatically improved the rash. Immunotherapy with pembrolizumab, an anti-PD-1 antibody, can induce T-cell activation that results in various immune-related adverse effects such as lichenoid tissue reaction. However, lichen planus is generally found on the extremities and/or oral mucosa, and unlike in this case, the scalp is rarely affected. Although the exact mechanism underlying predominant scalp involvement is unknown, the present case indicates that anti-PD-1 therapy-induced lichen planus can develop not only on the extremities and oral mucosa but also on the scalp. Interestingly, the lesions were not induced by the combination of chemotherapy and pembrolizumab; rather, they occurred soon after initiation of pembrolizumab monotherapy. In the present case, pembrolizumab-induced T-cell activation which triggered lichenoid tissue reaction may have been suppressed by chemotherapy-induced immunosuppression. Dermatologists should have a thorough knowledge of the cutaneous lesions that manifest as irAEs of anti-PD-1 therapy.

Erosive Pustular Dermatosis of the Scalp: A Clinicopathologic Study of Fifty Cases

Erosive pustular dermatosis of the scalp (EPDS) is an uncommon, pustular, idiopathic disorder typically occurring on the scalp of the elderly, whose diagnosis requires close clinicopathologic correlations. Recently, the primary histopathologic characteristic of EPDS has been identified in some biopsies from hair-bearing scalp lesions as a sterile, vesiculo-pustule involving the infundibulum of hair follicles. To further delineate the clinicopathologic spectrum of the disease, we led a retrospective study of 50 patients (36 males and 14 females) with a diagnosis of EPDS between 2011 and 2021, reviewing clinical and histopathological data. Androgenetic alopecia was present in 32 patients. Triggering factors were present in 21 patients. The vertex was the most common location; one patient also had leg involvement. Two cases were familial. Disease presentation varied markedly from tiny, erosive, scaly lesions to crusted and hemorrhagic plaques, mimicking pustular pyoderma gangrenosum (PPG). Biopsies of patients with severe androgenetic or total baldness produced specimens showing nonspecific pathologic changes (39/50), while in 11 patients with a hair-bearing scalp histopathologic examination, changes were specific. The clinicopathologic similarities between EPDS and PPG suggest that EPDS should be included in the spectrum of autoinflammatory dermatoses. Clinicians could consider the possibility of associated disorders rather than managing EPDS as a sui generis skin disorder.

Kerion Celsi in a Nepalese Boy: An Underdiagnosed Cause of Scalp Swelling

Tinea capitis (TC) is an infection of the scalp and hair caused by a dermatophyte fungus. Typically caused by the zoophilic and geophilic species of Microsporum and Trichophyton, it remains the commonest cutaneous fungal infection in children. A 9-year-old Nepalese boy was evaluated in outpatients for multiple boggy scalp lesions for two months. Suspecting a bacterial etiology, the lesions were excised and sent for cultures. While bacterial cultures failed to grow, endothrix spores were readily detected in potassium hydroxide preparation and histopathology. Trichophyton tonsurans was identified by the phenotype method and later confirmed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF). Systemic antifungal therapy for 6 weeks along with local wound dressings resulted in complete recovery. At 2-year follow-up, focal alopecia was seen; however, no recurrence was noted.

Skull Modulated Strategy to Intensify Tumor Treating Fields on Brain Tumor: a Finite Element Study

Purpose Tumor treating fields (TTFields) are a breakthrough in treating glioblastoma (GBM). Whereas, the intensity cannot be further enhanced, due to the limitation of scalp lesions. Skull remodeling (SR) surgery can elevate the treatment dose of TTFields in the intracranial foci. This study was aimed at exploring the characteristics of SR surgery towards TTFields augmentation. Methods The simplified multiple-tissue-layer model (MTL) model and realistic head (RH) model were reconstructed through finite element methods (FEM), to simulate the remodeling of the skull, which included skull drilling, thinning, and cranioplasty with PEEK, titanium, cerebrospinal fluid (CSF), connective tissue and autologous bone. Results Skull thinning could enhance the intensity of TTFields in the brain tumor, with a 10% of increase of average peritumoral intensity (API) by every 1 cm decrease in skull thickness. Cranioplasty with titanium accompanied the most enhancement of TTFields in the MTL model, but CSF was superior in TTFields enhancement when simulated in the RH model. Besides, API increased nonlinearly with the expansion of drilled burr holes. In comparison with the single drill replaced by titanium, 9 burr holes could reach 96.98% of enhancement in API, but it could only reach 63.08% of enhancement under craniectomy of 9-times skull defect area. Conclusion Skull thinning and drilling could enhance API, which was correlated with the number and area of skull drilling. Cranioplasty with highly conductive material could also augment API, but might not provide clinical benefits as expected. Keywords Tumor treating fields, skull remodeling, cranioplasty, skull replacement, brain tumor, finite element analysis

Development of squamous cell carcinoma in an untreated patient of psoriasis: a case report

In this article we report a case of SCC in an untreated 45-year-old male patient of psoriasis. The patient referred to the dermatology department manifesting erythrodermic psoriasis. After taking multiple biopsies from scalp lesions, the result was reported to be SCC with sebaceous differentiation.