A Rare Case of an Intrapulmonary Teratoma Masquerading as a Pulmonary Hamartoma.

Teratomas are fully formed germ cell tumors derived from multiple germ layers. While most commonly gonadal, they can occur in extragonadal sites, particularly the mediastinum. Isolated intrapulmonary teratomas without mediastinal extension are exceptionally rare, with fewer than 100 cases reported in the literature, and can be mistaken for other calcified lung lesions such as hamartomas. We report the case of a 57-year-old former smoker who presented with a three-month history of chest pain and dry cough. Chest X-ray and computed tomography (CT) scan revealed a large, well-circumscribed left lower lobe mass with central "popcorn" calcification, initially suggestive of a pulmonary hamartoma. Tumor markers were negative, and all other investigations were within normal limits. The patient underwent a left lower lobectomy via posterolateral thoracotomy. Histopathological examination revealed mature cartilaginous, adipose, bony, nervous, and glial tissues without any immature or malignant component, confirming the diagnosis of a mature intrapulmonary teratoma. The postoperative course was uneventful. Intrapulmonary teratoma, though rare, should be included in the differential diagnosis of calcified lung masses mimicking pulmonary hamartoma. Complete surgical resection remains both diagnostic and curative, with an excellent prognosis for mature forms, though long-term clinical and tumor-marker surveillance is warranted.