Ulcerative erythematous papules and plaques on the face and lower legs of a man living with HIV: a clinicopathological challenge.

A 44-year-old male presented with a 2-month history of erythematous ulcerative papules and plaques on the scalp, face, and bilateral lower legs. He had a 5-year history of well-controlled HIV on antiretroviral therapy and recurrent syphilis infections. His face had violaceous plaques, while bilateral ankles and calves had ulcerative lesions with necrotic centers and purple borders. The morphologies clinically mimicked pyoderma gangrenosum on the lower extremities and cutaneous lymphoma on the face. Biopsy and reactive rapid plasma reagin confirmed a diagnosis of lues maligna, and the patient was successfully treated with penicillin G benzathine.

Cost-effectiveness of patch testing allergens within the same group: A computational approach to optimize formaldehyde-related allergen selection.

BACKGROUND: Patch testing for multiple cross-reactive allergens for allergic contact dermatitis (ACD) may not be necessary because of copositivity. OBJECTIVES: We evaluated the formaldehyde group allergens to determine the optimal, most cost-effective allergens to test. METHODS: A retrospective analysis of Mayo Clinic (1997-2022) examined the well-established copositive formaldehyde group: formaldehyde, quaternium 15, hexahydro-1,3,5-tris(2-hydroxyethyl)triazine, diazolidinyl urea, imidazolidinyl urea, toluenesulphonamide formaldehyde resin, DMDM hydantoin, and ethyleneurea melamine formaldehyde mix. Patch Optimization Platform identified which single formaldehyde-related allergen optimally captures patients with clinically relevant ACD. Next, Patch Optimization Platform determined the optimal additional 1, 2, 3, etc. allergens. Cost per patch test was $5.19 (Medicare 2022). RESULTS: A total of 9832 patients were tested for all listed allergens, with 830 having positive patch test results. Patch Optimization Platform determined that quaternium 15 alone captures 53% of patients with ACD to the formaldehyde group; adding the optimal second allergen (formaldehyde 1%) captures 78%; the optimal 5 top allergens capture >94% of patients. The incremental cost per additional diagnosis increased up to 44-fold as the number of allergens tested increased. LIMITATIONS: Data are from a single institution, and the cost per test was fixed according to Medicare Part B in 2022. CONCLUSIONS: For diagnosing ACD, we recommend considering an optimized allergen selection algorithm.