Experts Present Cases of Complex Pigmented Lesions at Elevate-Derm West

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At the Elevate-Derm West Conference, in Scottsdale, Arizona, Mark Gimbel, MD, and Whitney High, MD, presented a series of challenging cases involving pigmented lesions, primarily focusing on the nuanced diagnostic process and potential pitfalls in managing melanocytic lesions. Through detailed histopathological analysis, immunostaining, and molecular testing, they highlighted the critical role of thorough investigation to distinguish between benign and malignant lesions, especially when initial presentations are ambiguous.

Case 1: Late 60s Woman with a Pigmented Lesion

The first case presented involved a woman in her late 60s who presented with a pigmented lesion, suspected to be either a benign nevus or an atypical nevus. The lesion was excised via shave biopsy, which unfortunately transected the lesion, leaving some uncertainty regarding the diagnosis. While the lesion initially appeared benign, further examination of the deeper, transected areas revealed atypical melanocytes, which raised concerns. Additional staining techniques, including p16 and HMB-45 immunostains, were applied to examine tumor suppressor proteins. High said the lesion showed reduced p16 expression in deeper areas and atypical HMB-45 patterns, suggesting potential malignancy. Further genetic testing, including comparative genomic hybridization, confirmed significant chromosomal abnormalities associated with melanoma. This case highlighted the importance of thorough histopathological evaluation and the need for comprehensive clinical information, as a superficial biopsy alone could have led to a missed melanoma diagnosis.

Case 2: Middle-Aged Man with a Recurrent Papule

The second case was of a 54-year-old man who lives in both Colorado and Belize, presenting with a recurring pearly papule on his shoulder. The lesion had been treated with liquid nitrogen, but it quickly recurred, raising suspicion for a potential melanoma. Initial histopathological assessment did not definitively confirm malignancy, though concerning characteristics like hyperchromatic and pleomorphic cells were observed. High stated that immunostaining showed a complete loss of p16 and positive PRAME staining, both indicators suggestive of melanoma. Additionally, satellite cells separated from the main tumor mass were observed, which raised questions about possible microscopic metastasis. The lesion was later confirmed as an amelanotic melanoma. This case emphasized the potential challenges of diagnosing subtle melanoma and the importance of tracking recurrent lesions closely.

Case 3: Patient with Misdiagnosed Melanoma Following Cryotherapy

The third case involved a patient with a misdiagnosed melanoma lesion that had been previously treated with cryotherapy. Upon closer examination of the biopsy, it was found that residual cells existed at the base, potentially due to prior cryotherapy causing cell separation. The team utilized multiple staining techniques, including p16 and PRAME, to further evaluate the lesion. The lack of a definitive diagnosis initially led to consultation with a second institution, which offered a differing opinion, classifying the lesion as a benign BAPoma. However, further testing confirmed melanoma, with both clinical and microscopic satellite metastasis noted. Ultimately, the lesion was reclassified as a metastatic melanoma with satellite foci, and the patient received immunotherapy as part of an updated treatment approach. This case highlighted the diagnostic complexities that can arise with cryotherapy-altered tissue and the need for multi-institutional consultation in challenging cases.

Key Takeaways

Throughout these cases, High emphasized the need for a cautious and comprehensive approach in dermatopathology, particularly when handling melanocytic lesions. He illustrated the limitations of relying solely on superficial or partial biopsies, which may miss malignant characteristics. He noted immunohistochemical staining plays a critical role in discerning malignancy, especially for markers like p16, HMB-45, and PRAME. Although these stains are not definitive alone, they provide significant insights, particularly in ambiguous or borderline cases.

Another key discussion point was the value and challenges of molecular diagnostics, such as comparative genomic hybridization, which can detect chromosomal abnormalities associated with melanoma. Gimbel highlighted that while molecular testing can provide crucial information, it is often costly and time-consuming. Both doctors noted the importance of maintaining a healthy skepticism toward initial findings, even when consulting with specialists, as experienced consultants can still make errors in complex cases.

Furthermore, Gimbel discussed evolving treatment protocols, including neoadjuvant immunotherapy, which may be more effective when administered with residual tumor present. This approach represents a shift from traditional management that favors immediate excision, emphasizing the importance of individualized treatment plans based on each patient’s unique circumstances and tumor behavior.

Overall, the presentations underscored the importance of a multi-modal approach in dermatopathology, where histological evaluation, immunostaining, molecular diagnostics, and clinical judgment collectively inform accurate diagnoses and effective treatment strategies for pigmented lesions. These cases highlighted the potential for misdiagnosis when relying solely on routine stains or superficial biopsies, as well as the crucial role of clear communication between dermatopathologists and clinicians. Through thorough investigation, continuous consultation, and innovative treatment approaches, clinicians can improve diagnostic accuracy and patient outcomes in challenging dermatological cases.