Dermatopathology Case Challenge: Recognizing Mimics and Masqueraders

In this dermatopathology case challenge, Dr. Michi Shinohara presented three significant cases illustrating the complexities of diagnosing skin conditions that can mimic one another. The first case involved a 92-year-old man with metastatic urothelial carcinoma who developed skin desquamation, initially suspected to be toxic epidermal necrolysis (TEN). However, through a dermatoscopic technique known as the "Jelly roll," a superficial skin sample indicated a non-full thickness necrosis due to a reaction from the drug enfortimab, distinguishing it from typical TEN. The second case described an 18-year-old woman with a history of hemophagocytic syndrome who showed skin lesions resembling panniculitis. A thorough examination and biopsy indicated subcutaneous panniculitis-like T-cell lymphoma, despite her systemic condition being present as well. Lastly, a 150-year-old man with a nodule on his back was diagnosed with cutaneous involvement of systemic follicular lymphoma, highlighted by the presence of B-cell markers and confirmed through PET scanning, demonstrating extensive node involvement. The cases emphasized the importance of specific diagnostic techniques and stains, such as Ki-67 and BCL-2, in differentiating between conditions and stressed the necessity for thorough evaluations in complex dermatopathological cases.