Multiple myeloma masquerading as chromophobe adenoma

Area of Science:

• Neuropathology
• Oncology
• Endocrinology

Background:

• Plasmacytoma is a rare plasma cell tumor that can occur in the pituitary region.
• Intracranial lesions in the sellar region can present diagnostic challenges.
• Distinguishing pituitary plasmacytoma from other sellar masses, such as pituitary adenomas, is crucial for appropriate management.

Observation:

• A 62-year-old woman presented with an intracranial lesion eroding the sella and compressing the optic chiasma.
• Initial surgical assessment and light microscopy suggested a chromophobe adenoma.
• The patient lacked biochemical, immunologic, or bone marrow evidence of multiple myeloma at the time of diagnosis.

Findings:

• Electron microscopy definitively diagnosed the intracranial tumor as plasmacytoma.
• This diagnosis was made despite initial light microscopy findings suggestive of a pituitary adenoma.
• The tumor's location was the pituitary area, causing significant mass effect.

Implications:

• This case underscores the importance of electron microscopy in diagnosing rare pituitary and sellar region tumors.
• Accurate diagnosis of pituitary plasmacytoma is essential for guiding treatment strategies.
• Electron microscopy can reveal the true nature of tumors that are misdiagnosed by conventional methods.