Faculty Bibliography

Penoscrotal skin diseases encompass an array of pathologies that present with unique clinical features. A patient-tailored approach to management is necessary. This article, part of a continuing medical education series, is dedicated to offering insights for managing penoscrotal dermatoses. The first article will provide an overview of normal variations, benign lesions, and malignant growths. We will then highlight up-to-date diagnostic and treatment protocols. In the second article, we will discuss inflammatory and infectious conditions, reviewing common diseases such as syphilis, human papilloma virus, and psoriasis, as well as rarer, difficult to treat diseases such as lichen sclerosus, lichen planus, and genital dyesthesias. Considering 70% of patients with genital skin diseases report that physicians lack awareness of these conditions,¹ this CME series will help practitioners identify penoscrotal diseases, expand differential diagnoses, and discuss appropriate and emerging therapies.

Erdheim"“Chester disease (ECD) is a rare, non-Langerhans histiocytic disease, with the manifestation of cutaneous lesions becoming further recognised and understood. Most commonly presenting with xanthelasma-like lesions, cutaneous manifestations are the first noticeable sign of ECD in a significant number of patients. Other commonly reported cutaneous lesions of ECD include panniculitis-like lesions and granuloma annulare-like lesions. While previously reported papular lesions of ECD include crusty yellow and erythematous papules, small, pink to fleshy coloured papules, and verruca plana-like papules, papulonodular eruptions consistent with fibrous histiocytomas are a rare and underreported sequala of ECD. Here, we report an 86-year-old male with a history of prostate and bladder cancer who presented with eruptive fibrous histiocytomas, prompting workup that lead to a diagnosis of ECD. The patient received expedited imaging given the rare association of eruptive fibrohistiocytic lesions with malignancy, revealing diffuse perinephric and urothelial soft tissue thickening and enhancement, which was biopsied and found to harbour the BRAF V600E mutation. One could reasonably hypothesise that the pathologic mechanism occurring in the perinephric and urothelial soft tissue areas of this patient bodes similarities to the cutaneous sites consistent with the fibrohistiocytic lesions. This may present a potential clue to the poorly understood origin and pathogenesis of ECD.

BACKGROUND Acute myeloid leukemia is characterized by dysregulated proliferation and maturation arrest of myeloid precursors, precipitating a spectrum of complications. Among these, leukemia cutis refers specifically to ectopic deposition and proliferation of malignant myeloid cells within the skin. This infiltration pathogenesis remains unclear. Although there are numerous reports of leukemia cutis in the setting of acute myeloid leukemia or primary acute myeloid leukemia, there are no specific reports of leukemia cutis in the setting of relapsed acute myeloid leukemia. CASE REPORT A 59-year-old woman, with a history of remission from poor-risk acute myeloid leukemia, previously treated with chemotherapy and allogenic bone marrow transplant, presented with shortness of breath, lethargy, anemia, thrombocytopenia, and subcutaneous nodules on lower extremities. Leukemia cutis was diagnosed, in the setting of relapsed acute myeloid leukemia. After unsuccessful salvage chemotherapy and being deemed unsuitable for further treatment, she pursued palliative care and died a month later. CONCLUSIONS Our case highlights a lack of reporting or making a distinction of those patients with relapsed acute myeloid leukemia and leukemia cutis. Consequently, it can be deduced that patients who simultaneously have relapsed acute myeloid leukemia and leukemia cutis are expected to fare worse in terms of clinical outcomes than those with primary acute myeloid leukemia and leukemia cutis. Relapsed acute myeloid leukemia patients with leukemia cutis should be classified as a distinct group, warranting further research into aggressive therapeutic targets and survival rates, while emphasizing the need for more vigilant follow-up and lower biopsy thresholds for cutaneous lesions in patients with treated hematologic malignancies.