Abstract
Malignant melanoma, a cancer type with a high mortality rate and increasing incidence worldwide, primarily affects the skin but can also occur in various other organs and tissues, including the respiratory tract. Although primary lung malignant melanomas are rare, they are often diagnosed at advanced stages due to their asymptomatic nature, and their atypical presentations may lead to misdiagnosis as other malignancies. In this case report, a mass lesion almost completely filling the right lung initially led to the consideration of small cell lung carcinoma, but a definitive pathological diagnosis could not be obtained in subsequent studies. The diagnosis was confirmed by soft tissue biopsy taken from the anterior thoracic wall. Considering clinical, pathological, and radiological evaluations, possible diagnoses included sarcoma, small-cell lung cancer, and melanoma. The patient, diagnosed through multiple tissue sampling and detailed dermatological examination, presents an interesting atypical case. This case highlights that rare variants of melanoma can be mistaken for other cancer types, such as lung cancer, sarcoma, or lymphoma. Patients may not always present with a noticeable skin lesion; therefore, a meticulous skin examination is crucial in such cases. Malignant melanoma is a noteworthy disease, considering its increasing incidence and early diagnosis holds vital importance for appropriate treatment and management.