Update on hypophysitis and TTF-1 expressing sellar region masses

Area of Science:

• Endocrinology and Neurosurgery
• Pituitary Gland Disorders
• Sellar Region Mass Differential Diagnosis

Background:

• Nonsecretory pituitary adenomas are often mimicked by other sellar region masses, complicating clinical and radiological diagnosis.
• Accurate differentiation is crucial as these entities frequently require biopsy or surgical resection for definitive diagnosis.
• Recent literature has expanded understanding of hypophysitis and related neoplastic conditions.

Observation:

• Four entities—hypophysitis, pituicytoma, spindle cell oncocytoma, and granular cell tumor of the neurohypophysis—present diagnostic challenges.
• Distinguishing these masses preoperatively based on clinical or imaging features remains difficult.
• New forms of hypophysitis, including IgG4 plasma cell hypophysitis and therapy-induced hypophysitis, have been identified.

Findings:

• Immunohistochemical staining for thyroid transcription factor-1 (TTF-1) is common to pituicytoma, spindle cell oncocytoma, and granular cell tumor, suggesting a shared cell lineage.
• This shared lineage explains the histological overlap observed between these neoplastic conditions.
• Review incorporates 30 years of experience from specialized pituitary mass centers.

Implications:

• Accurate pathological diagnosis is essential for appropriate management of sellar region masses.
• Understanding shared markers like TTF-1 aids in classifying these tumors and differentiating them from hypophysitis.
• Continued research and clinical experience are vital for improving diagnostic accuracy and patient outcomes.