A Rare Case Of Nodular Melanoma With Extensive Reactive Squamous Epithelial Proliferation: Diagnostic Challenges And Pathological Insights

Abstract

Background:

Among the various subtypes of cutaneous melanoma, nodular melanoma is considered the most aggressive, characterized by a high metastatic potential, rapid vertical growth, and deep tissue invasion. Acral melanoma, although relatively rare, poses diagnostic challenges due to its subtle clinical presentation and resemblance to benign ulcers.

In this case report, we describe a case of nodular melanoma presenting as a non-healing ulcer on the foot, with histological findings notable for extensive adjacent reactive squamous epithelial proliferation.

Case Presentation:

An 82-year-old male presented with a non-healing ulcer on the plantar aspect of the right heel, persisting for one year. The patient underwent wide local excision of the lesion along with an inguinal block dissection. Gross examination revealed an ulceroproliferative lesion measuring 7 × 6 cm, with prominent brownish-black discoloration. Microscopic examination demonstrated a nodular malignant melanoma with a Breslow thickness of 8 mm, Clark level V invasion, and ulceration exceeding 2 cm in diameter.Notably, extensive adjacent reactive squamous epithelial proliferation was observed, characterized by dyskeratotic cells, keratin pearl formation, and melanin pigment deposition. Despite these features mimicking squamous cell carcinoma, immunohistochemistry confirmed the diagnosis of malignant melanoma.

Conclusion:

This case underscores the diagnostic challenges associated with melanoma, particularly when it presents with features mimicking squamous cell carcinoma. It highlights the crucial role of immunohistochemistry in distinguishing between these entities. Accurate histopathological evaluation is essential for appropriate treatment planning and prognostication, especially in lesions exhibiting biphasic or misleading morphological features.