Coexistence of Multiple Endocrine Neoplasia Type 2B and Centri-Acinar Emphysema With Alpha-1 Antitrypsin Deficiency: A Case Report.

Alpha-1 antitrypsin deficiency (AATD) is a hereditary disorder that reduces a key lung-protective protein, predisposing individuals to early-onset emphysema. Multiple Endocrine Neoplasia type 2B (MEN2B), caused by RET gene mutations, is a rare syndrome characterised by aggressive medullary thyroid carcinoma and pheochromocytoma. Coexistence of MEN2B and AATD has not previously been reported. A 32-year-old woman with a history of medullary thyroid carcinoma and prior total thyroidectomy presented with severe dyspnea, generalised edema and weakness after discontinuing levothyroxine. She was tachycardic and hypoxemic, with wheezing and bilateral crackles. Laboratory evaluation showed leukocytosis, thrombocytosis, electrolyte abnormalities and markedly reduced alpha-1 antitrypsin levels. Chest CT revealed bilateral cystic and emphysematous changes, and spirometry confirmed severe obstructive disease. Supportive therapy and symptom-directed management improved her respiratory status. The diagnoses of MEN2B and AATD were made based on clinical features, biochemical findings and imaging results, as confirmatory genetic testing was not available according to sanction. This case highlights the extremely rare coexistence of MEN2B and AATD. Overlapping manifestations contributed to delayed recognition. Clinicians should consider rare genetic conditions when common diagnoses do not fully explain a patient's presentation.