Primary malignant melanoma of lung: A clinical, radiological and cytological correlation

Background: Primary malignant melanoma of the lung (PMML) is an extremely rare neoplasm, accounting for only 0.001% of all pulmonary tumors. While malignant melanoma commonly presents as skin lesions, primary lung involvement is exceptionally uncommon, with only 45 cases reported globally by 2018. This case report presents a rare instance of PMML in a 70-year-old Indian male. Case Presentation: A 70-year-old gentleman presented with progressive dyspnea, chest pain, and unintentional weight loss. HRCT thorax revealed a large 76×96×75 mm mass in the left upper lobe with rib erosion and pathological fracture. USG-guided transthoracic FNAC demonstrated dyscohesive tumor cells with intracytoplasmic brownish pigments and pleomorphic nuclei consistent with malignant melanoma. Comprehensive evaluation excluded extrapulmonary primary sites, meeting Jensen and Egedorf diagnostic criteria for PMML. Immunohistochemical confirmation was not performed due to financial constraints. Outcome: The patient declined surgical and chemotherapeutic interventions and expired four months post-diagnosis, consistent with the poor prognosis associated with PMML. Conclusion: This case highlights the diagnostic challenges and aggressive nature of PMML in resource-limited settings. Early recognition and aggressive multimodal treatment may improve outcomes, though prognosis remains poor with median survival of 18 months.