Hypertrophic lichenoid dermatitis immune-related adverse event during combined immune checkpoint and exportin inhibitor therapy: A diagnostic pitfall for superficially invasive squamous cell carcinoma.

Immune checkpoint inhibitors (ICIs) for cancer treatment have revolutionized the field of medicine. However, an unintended but frequent consequence of ICI therapy is the development of cutaneous immune-related adverse events (irAEs), such as lichenoid dermatitis irAEs (LD-irAEs). The hypertrophic variant of LD-irAE may be a diagnostic challenge since it can mimic superficially invasive squamous cell carcinoma (SCC). A 79-year-old woman with metastatic melanoma who began treatment with an ICI-pembrolizumab-plus exportin-1 (XPO1) inhibitor presented after 1 month of therapy with symmetrical violaceous papules coalescing into plaques and with two nodules of the bilateral dorsal hands. Biopsy of the nodules revealed an actinic keratosis and atypical epidermal proliferation concerning for SCC. However, in the ensuing 3 weeks, the patient developed multiple new erythematous, violaceous, and scaly macules and papules, some coalescing into plaques on the extremities. Biopsies of these lesions revealed exuberant irregular epidermal hyperplasia with hypermaturation and lichenoid infiltrate concentrated at the base of the elongated, broadened rete ridges, consistent with hypertrophic LD-irAE. Treatment included topical fluocinonide ointment, intralesional triamcinolone injections and oral acitretin. Distinguishing hypertrophic LD-irAE and SCC can be challenging since both entities share histopathologic features; thus, correlation with clinical presentation is essential for diagnosis and optimal patient management.

Juvenile xanthogranuloma: A herald to the diagnosis of Erdheim-Chester disease in an adult with acute leukemia.

A 21-year-old man with B-cell acute lymphoblastic leukemia developed an eruption of multiple flesh-colored nodules and persistent fevers. A lesional biopsy showed diffuse dermal infiltrates of histiocytes, foam cells, and Touton giant cells consistent with juvenile xanthogranulomatosis. Upon further investigation, the patient's constellation of findings fit criteria for Erdheim-Chester disease.

Incidental finding of a true human tail in an adult: a case report.

True human tails are rare vestigial structures that are typically removed in childhood. Here a case is presented in which an inconspicuous sacrococcygeal tail was incidentally discovered in late adulthood. A 56-year-old man with no significant past medical history presented to a dermatology clinic with a chief complaint of a hyperpigmented lesion on his central back. However, on full body skin exam, a separate flesh-colored 0.7 cm × 0.5 cm appendage was discovered in the midline sacrococcygeal region. This lesion had been present and unchanged since childhood. This particular lesion was removed via shave biopsy. Microscopic exam found it to be consistent with a diagnosis of a true human tail. There were no apparent involved spinal cord structures, and no further treatment was thought to be necessary. Human tails are congenital anomalies associated with occult spinal lesions in about 50% of cases. Therefore, it is in these patients' best interest to thoroughly evaluate for spinal cord involvement prior to biopsy. There is a relative lack of literature published on the topic, and a greater awareness of human tails would be helpful to ensure their inclusion in a differential diagnosis for persistent sacrococcygeal lesions in patients of any age.