Case report: Study of a bulky melanoma mimicking sarcoma

Large melanomas, while relatively uncommon, present significant diagnostic challenges due to their size and potential to mimic other malignancies, leading to delays in appropriate treatment. Initial misdiagnosis is a substantial concern, impacting patient outcomes. This case highlights the importance of immunohistochemistry in cancer diagnosis, and of appropriate therapeutic management, which here included excision surgery of the tumor mass.

This case report details a 75-year-old male who presented with a large mass on his left arm, initially hypothesized as a liposarcoma. Advanced imaging (MRI) and immunohistochemical analysis revealed the mass to be a superficial spreading melanoma expressing SOX10, PS100, Melan-A, HMB-45, and PRAME.

The patient later presented other skin lesions. As melanoma increase the risk of developing skin tumors, it is conceivable that the lesions may be interconnected. However, the lack of invasion beyond the dermis and the absence of metastasis suggest otherwise. The patient's psychological profile was investigated as another potential risk factor of cancer development. Inflammatory microenvironment was also observed, linked to the bacterial superinfection in the site of the initial tumor.

This case underscores the considerable diagnostic challenges caused by large melanomas, especially their potential for mimicking other malignancies. Biopsy, incorporating advanced imaging and immunohistochemistry, is crucial for accurate and timely diagnosis, enabling appropriate management and improving patient outcomes. This case emphasizes that, when possible, surgery should be performed regardless of the size of the tumor. Long-term surveillance is vital given the increased risk of subsequent skin cancers in such patients.