A rare case of cutaneous granular cell tumor with unusual Melan-A expression in a child.

Granular cell tumors (GCTs) are rare, indolent neoplasms classically characterized by eosinophilic granular cytoplasm, infiltrations of polygonal cells in the collagenous stroma, and pustulo-ovoid bodies of Milian. We describe a case of a 10-year-old female presenting with a GCT of the upper arm, remarkable for positive Melan-A expression without additional melanocytic features. The differentiation between granular cells versus melanocytic neoplasms carries significant implications for clinical management, and such diagnoses should be considered carefully in the setting of unusual immunophenotypes.

Whole-Exome Sequencing of a Case of Squamoid Eccrine Ductal Carcinoma Reveal Similarities With Cutaneous Squamous Cell Carcinoma.

ABSTRACT: Squamoid eccrine ductal carcinoma (SEDC) is a poorly documented but likely underrecognized sweat gland malignancy with significant risk for local recurrence and potential for metastasis and rare disease-related mortality. Histopathologically, the tumor demonstrates a biphasic differentiation pattern: superficially, the tumor has squamous differentiation [indistinguishable from well-differentiated cutaneous squamous cell carcinoma (cSCC)], while the deeper aspect has a more infiltrative pattern with prominent ductal differentiation. Diagnosis of SEDC relies upon histopathologic examination alone. Its pathogenesis is poorly understood, and its genomic features have yet to be described. In this article, we characterize the genomic features in a case of SEDC through whole-exome sequencing, then compare its features with cSCC and other eccrine ductal carcinomas. Whole-exome sequencing revealed 30 mutations/Mb with 21 pathogenic or likely pathogenic mutations in total, identified across 14 different genes. The genomic abnormalities identified in this case of SEDC overlap considerably with those found in cSCC but not those of other sweat gland malignancies. The clinical and histopathologic features of SEDC previously reported and the genetic features determined from this case suggest that this tumor may arise initially as a well-differentiated cSCC that subsequently undergoes divergent differentiation focally to resemble a sweat gland malignancy. Genetic analyses of additional cases are warranted to clarify this consideration.

Lichen Planus Pemphigoides Associated With PD-1 and PD-L1 Inhibitors: A Case Series and Review of the Literature.

ABSTRACT: Immune checkpoint inhibitors are increasingly being used in the treatment of various solid organ and hematologic malignancies. Dermatologic toxicities associated with programmed cell death protein-1 (PD-1) and programmed death ligand-1 (PD-L1) therapy have been widely reported in the literature. It is important for clinicians to be aware of these toxicities to ensure prompt recognition and treatment. Herein, we present the clinical, histopathologic, and immunofluorescence findings of 3 patients diagnosed with lichen planus pemphigoides (LPP) after treatment with anti-PD-1 inhibitors. We also reviewed the literature and summarize 7 previously reported cases of LPP associated with anti-PD-1 and anti-PD-L1 inhibitors. LPP was diagnosed at a median time of 24.4 weeks (range: 4-78 weeks) after initiation of immunotherapy. Clinical findings included papules, plaques, erosions, vesicles, and bullae on the trunk and extremities. Oral involvement was present in half the cases. Histopathologic features of immunotherapy-induced LPP included lichenoid or vacuolar interface dermatitis, the presence of eosinophils, and subepidermal bullae. Direct immunofluorescence demonstrated linear deposition of immunoglobulin G (IgG) or C3. Indirect immunofluorescence demonstrated linear IgG along basement membrane zone on monkey esophagus in 2 cases and linear IgG on the epidermal side of salt split skin in 3 cases. Serum anti-BP180 was elevated in all cases in which enzyme-linked immunosorbent assay was performed.

Follicular keratosis of the face in pediatric patients of color.

BACKGROUND/OBJECTIVES: Follicular keratosis (FK) is a poorly understood disorder presenting with multiple, grouped hyperkeratotic follicular papules typically affecting the chin or jawline. This study describes the clinical presentation, histopathology, management, and outcomes of a series of pediatric patients of color with FK of the face, thought to be related to rubbing or friction on the skin. METHODS: Retrospective review of 20 pediatric patients with FK of the face who presented to our pediatric dermatology practice between April 2019 and October 2021. RESULTS: Twenty patients (mean age 12.1 years, 13 females), all self-identified as Black/African American, were included. All presented with an initially asymptomatic, hyperpigmented patch containing multiple hyperkeratotic follicular papules, located on the cheek, chin, upper lip, and/or jawline. Five patients endorsed a history of rubbing the site. Nine patients had onset of the lesions during the COVID-19 pandemic. Treatments included topical vitamin D analogs, corticosteroids, and/or retinoids. Topical vitamin D analogs and retinoids improved the texture and hyperpigmentation of the follicular lesions in only four patients, while topical corticosteroids had no effect. Histopathological examination of two patients revealed multiple dilated follicles containing keratinized material and associated with a sparse dermal inflammatory infiltrate in one patient and granulomatous inflammation within the dermis in the other. CONCLUSIONS: In our cohort of pediatric patients with FK, patients of color were preferentially affected, and all cases were associated with hyperpigmentation. Some patients presented during the COVID-19 pandemic suggesting that friction from facial mask wearing may have induced or exacerbated this uncommon condition.