Pretibial myxedema, more generally thyroid dermopathy, results from mucopolysaccharide accumulation in the dermis, typically between the knee and dorsal foot. Thyroid dermopathy presents in Graves disease, but can occur in Hashimoto thyroiditis, primary hypothyroidism, and euthyroid patients. Treatment of thyroid eye disease with teprotumumab is established in the literature, with few case reports also showing improvement in pretibial myxedema. Reported is a 76-year-old man with thyroid eye disease and pretibial myxedema treated with teprotumumab; improvement was demonstrated in both conditions. He developed "muffled" hearing as an adverse effect, a complication not widely published in the dermatology literature. At 18 months post-treatment, his symptoms are stable without recurrence, but hypoacusis persists. Given the long-term efficacy and side-effects, dermatologists should recognize the potential benefits and risks of using teprotumumab for thyroid dermopathy. A baseline audiogram may be considered prior to therapy. Additionally, longitudinal data is needed to document the benefits and risks of this novel therapy.

The significance of basal cell carcinoma (BCC) invading the intravascular space is unknown. We report a case of an infiltrative BCC on the scalp that showed evidence of both intravascular and perineural invasion. The tumor locally recurred in the bone marrow space 4.5 years following the initial procedure. Since recurrence and metastasis of BCC can be delayed for many years, we recommend long term follow-up for tumors showing aggressive features.

Targeted therapy (BRAF/MEK inhibitors) is frequently employed in the treatment of metastatic melanoma following immune checkpoint inhibitor therapy inefficacy or intolerance. Although BRAF inhibitors are commonly associated with cutaneous eruptions, they rarely cause severe cutaneous adverse drug reactions such as drug-induced hypersensitivity syndrome (DIHS). Drug-induced hypersensitivity syndrome is a severe drug reaction characterized by extensive eruption often seen in conjunction with fever, facial edema, lymphadenopathy, eosinophilia, atypical lymphocytosis, and variable visceral organ injury characteristically beginning 2-8 weeks after initiating the causative drug. We report a case of atypical DIHS with reduced latency, mucosal involvement, lymphopenia, normal eosinophils, and no lymphadenopathy that occurred secondary to vemurafenib and cobimetinib therapy following melanoma progression while on pembrolizumab. Previous immune checkpoint inhibitor therapy has been associated with atypical DIHS in patients on BRAF/MEK inhibitors. Early recognition of the atypical clinical features of this hypersensitivity reaction is important so that drug discontinuation and corticosteroids can be initiated early.

Hidradenitis suppurativa is a poorly understood, destructive disease centered on pilosebaceous units and characterized by inflammatory nodules that progress to abscesses, sinus tracts, and scars. The typical patient is a young woman with involvement of the axillae, breasts, and groin. Presented is a 60-year-old man with poorly controlled diabetes, who initially developed pink-to-yellowish plaques with punched out ulcers on his knees that evolved to scars and draining sinus tracts. Draining sinus tracts were also noted under the left axilla. Histopathology revealed suppurative granulomatous inflammation centered on hair follicles as well as sinus tracts. Special stains for fungus and mycobacterial bacilli were negative. Cultures and PCR for mycobacterial tuberculosis were negative. The patient was diagnosed with hidradenitis suppurativa. A treatment trial of topical corticosteroids and antibiotics was given, but this regimen failed to improve his lesions. The patient was then started on adalimumab, which yielded marked improvement within three months. This case is reported because of the unusual clinical presentation and to highlight the spectrum of atypical hidradenitis suppurativa.

Linear porokeratosis is a rare variant of porokeratosis that is characterized by unilateral lesions along the lines of Blaschko. Like all variants of porokeratosis, linear porokeratosis is characterized by the histopathologic finding of cornoid lamellae bracketing the lesion. The underlying pathophysiology involves a two-hit post-zygotic knockdown of genes involved in mevalonate biosynthesis in embryonic keratinocytes. Although there is currently no standard or effective treatment, therapies targeted to rescue this pathway and restore keratinocyte cholesterol availability are promising. Presented here is a patient with a rare, extensive case of linear porokeratosis treated with compounded 2% lovastatin/2% cholesterol cream leading to partial resolution of the plaques.

We present a case of a female patient who presented with a 0.6cm flesh-colored "rubbery" papule on the left thigh. Biopsy revealed a dermal myxoid tumor containing spindled cells, tapered nuclei, indistinct cell borders, and a large number of mast cells. The spindle cells stained negative for S100 protein and Sox10 on immunohistochemistry, excluding myxoid neurofibroma, but positive for epithelial membrane antigen (EMA), and CD34, supporting a diagnosis of myxoid perineurioma. Interestingly, the mast cells showed cytoplasmic and nuclear positivity for microphthalmia transcription factor (MiTF). The lesion was fully excised one year later with identical histopathology and ancillary immunohistochemical profile.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a cutaneous drug reaction that presents with symmetrical erythema in the flexures. The reaction typically appears hours-to-days after drug exposure but has been reported to occur months after drug initiation. Diagnostic criteria include cutaneous reaction after exposure to a systemic drug, erythema of the gluteal region and/or V-shaped erythema of the inguinal areas, involvement of an additional intertriginous site, symmetry, and absence of systemic involvement. The rash typically presents as macular erythema. However, variations in morphology have been reported including papules, pustules, vesicles, and bullae. The histopathology of SDRIFE is non-specific and the diagnosis is made clinically. Cessation of the causative drug leads to gradual rash resolution. Beta-lactam antibiotics are the most implicated medications but case reports describe SDRIFE following monoclonal antibodies, chemotherapeutic agents, and various other medications. We present a patient with SDRIFE secondary to lenalidomide, an immunomodulatory agent. This case highlights the importance of considering SDRIFE in the differential diagnosis of patients presenting with intertriginous erythema.