A man in his mid-70s with a sellar mass

Area of Science:

• Endocrinology
• Oncology
• Neuropathology

Background:

• Metastatic tumors to the pituitary gland are uncommon, with melanoma being a rare primary source.
• Pituitary oncocytomas are benign adenomas typically arising from pituitary cells.

Observation:

• A 76-year-old male with a history of subungual acral lentiginous melanoma presented with visual disturbances and loss of consciousness.
• Imaging revealed metastatic disease and a pituitary fossa mass with suprasellar extension and bony destruction.
• Surgical resection showed an admixture of pituitary adenoma and invasive metastatic melanoma.

Findings:

• Histopathological examination confirmed metastatic melanoma invading a pituitary oncocytoma.
• Melanoma cells were positive for S-100 protein and BMB-45.
• The pituitary adenoma component showed ultrastructural features of abundant mitochondria characteristic of oncocytomas.

Implications:

• This case highlights the rare occurrence of melanoma metastasis to a pituitary oncocytoma.
• It underscores the importance of considering metastatic disease in pituitary masses, especially in patients with a history of melanoma.
• Further research into the metastatic potential of various primary tumors to pituitary adenomas is warranted.