Malignant melanoma with pituitary metastasis: A case report and literature review.

Purpose: Pituitary metastasis of malignant melanoma (MM) is rare. This study aimed to explore its diagnostic features using a multimodal approach and retrospectively analyzed previously reported cases to summarize its pathogenesis and diagnostic challenges. Methods: We screened all published case reports and case series on pituitary metastatic MM using PubMed, focusing on cases with detailed clinical data, imaging features, pathological examination, and molecular test results. A total of 24 cases of MM with pituitary metastasis, including our case, were retrospectively analyzed. Additionally, the index patient underwent histopathological, immunohistochemical (S100, SOX10, Melan-A, HMB-45, BRAF V600E), and BRAF V600E PCR analyses. Results: This case involved a 65-year-old female patient whose pathological examination revealed tumor cells with epithelioid and spindle cell features. Immunohistochemical analysis showed diffuse positivity for S-100, vimentin, and BRAF V600E, with focal positivity for Melan-A and HMB-45. The Ki-67 proliferation index was approximately 15%. Molecular testing confirmed BRAF V600E mutation. The patient died 12 months postoperatively. Our literature review indicated that MM with pituitary metastasis demonstrates male predominance, a median onset age of 62 years, a frequent association with BRAF V600E mutation, and a median survival time of 12 months. Conclusion: Diagnosing MM with pituitary metastasis requires integrating detailed clinical history, imaging features, pathological examination, and molecular testing. Our findings highlight the importance of a comprehensive diagnostic approach with multidisciplinary collaboration when managing atypical pituitary masses, along with detailed investigation of a patient's previous tumor history, to improve diagnostic accuracy and patient outcomes.