Common and Uncommon Pitfalls in Clinicopathologic Correlation

Dr. Olayemi Sokumbi discussed three patient cases that demonstrate pitfalls in clinicopathologic correlation (CPC), the correlation between clinical and histopathological diagnosis. She believes that the gold standard for diagnosis involves collaboration between the dermatologist and dermatopathologist.

Case #1: Double whammy

A 28-year-old male presented with scattered plaques and nodules on his arms and legs. He was diagnosed four years earlier with lupus panniculitis and treated with azathioprine for two years. As the lesions progressed, he was treated with methotrexate and prednisone unsuccessfully. With repeat biopsies, Dr. Sokumbi diagnosed the patient with primary cutaneous gamma delta T cell lymphoma. He was treated with chemotherapy and died 54 months after initial presentation.

Dr. Sokumbi discussed the clinical and histopathologic pitfalls in this case. Clinicians need to know that lupus panniculitis and panniculitis-like lymphoma can be clinically and histopathologically similar.

Case #2: Staying superficial

An 82-year-old male presented with an axillary lesion. It appeared 10 years prior and recently increased in size and discomfort. Clinical impression was concerning for e hidradenitis suppurativa. The initial sample was a superficial shave biopsy that demonstrated an inconclusive superficial basaloid neoplasm that was sent to Dr. Sokumbi for a second opinion. Dr. Sokumbi asked for an additional sample and diagnosed the patient with adenoid cystic carcinoma (ACC). The patient was treated with wide, local excision of the axillary mass, lymphnode examination and radiation.

ACC is a rare, slow-growing neoplasm typically involving the salivary glands. It usually presents as a solitary lesion on the head and neck in middle-aged or elderly individuals. This case demonstrates the pitfall of performing a biopsy too superficially. Dr. Sokumbi emphasized that clinicians must consider the site thickness and depth of pathology of interest when choosing where to biopsy and what type of biopsy to perform.

Case #3: Evolving story

A 65-year-old female on treatment for advanced intrahepatic cholangiocarcinoma presented with a painful eruption on her legs. The clinical impression was consistent with retiform purpura, and the biopsy demonstrated an occlusive vasculopathy, but the work-up did not identify a cause. Dr. Sokumbi consulted hematology colleagues who suggested treatment with rivaroxaban. Shortly thereafter, the patient shared that she was in severe pain and the lesions has progressed. Dr. Sokumbi requested an incisional biopsy for more subcutaneous tissue for evaluation and it revealed histopathologic features of calciphylaxis. She learned from colleagues that the patient had a fibroblast growth factor receptor 2 (FGFR2) mutation and had started treatment with the FGFR inhibitor, pemigatinib one month before eruption onset. Dr. Sokumbi diagnosed the patient with calciphylaxis secondary to FGFR inhibitor. She stopped pemigatinib, and recommended management for hyperphosphatemia (high serum phosphate levels).

Calciphylaxis is a rare condition with high mortality that can occur secondary to treatment with FGFR inhibitor such as pemigatinib. This case demonstrates that CPC requires complete clinical information and that an evolving patient history may require reconsideration of histopathologic diagnosis.

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