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Adenoid Cystic Carcinoma Presenting as a Tracheal Polyp

1. Abstract Tumours primarily involving the trachea are very rare, Adenoid Cystic Carcinoma accounts for most cases after Squamous Cell Carcinoma. Adenoid cystic carcinoma of the airway originates from the submucosal glands of the tracheobronchial tree. These tumours pose a diagnostic and therapeutic challenge because of their slow growth and tendency for local recurrence and late metastasis. We present a case of adenoid cystic carcinoma of the trachea masquerading as a tracheal polyp clinically. 2. Introduction Adenoid cystic carcinoma (ACC) also known as cylindroma is a malignant tumour of salivary gland origin, first reported by Billroth in 1856. These neoplasms most commonly involve the parotid gland and account for 10% of tumours of the head and neck. These tumours arise from both major and minor salivary glands; therefore can occur in any head and neck site containing salivary gland tissue. Primary tracheal tumours are extremely rare, accounting for approximately 0.2 % of the entire respiratory system and 80 % of these are malignant. Adenoid cystic carcinoma (ACC) is the second most common primary malignant tumour of the trachea, after squamous cell carcinoma. The most common signs and symptoms are those of upper airway obstruction including dyspnoea, cough, haemoptysis, and stridor which are often insidious, delaying diagnosis and optimal management [1-3]. 3. Case Report A forty-six-year-old female presented to the outpatient department with complaints of coughing and wheezing for few months. The patient gave no history of fever or chest pain or any other history significant for suggesting laryngeal involvement. Her vital signs were within normal limits with no cervical or generalized lymphadenopathy. She was clinically euthyroid. There was no significant past or family history. A pulmonary function test (PFT) done outside showed mild restrictive pattern and the treadmill test (TMT) result was negative. She had taken symptomatic treatment from local alternative medicine practitioners and was also started on anti-histaminics with no relief. Cardiovascular and respiratory systems also were clinically normal. There was no thyroid gland enlargement or thyroid cartilage tenderness, and no cricothyroid escape. Laryngeal crepitus was present. Upon performing laryngoscopy, a growth was observed over the anterior wall of trachea. An incisional biopsy was performed which showed a sub epithelial tumour composed of uniform bland basaloid cells arranged in a cribriform pattern with myxohyaline material & foci of hemorrhage & necrosis with histiocytic & giant cell reaction. The biopsy was reported as suggestive of a Salivary Gland Type Tumour – favor Adenoid Cystic Carcinoma (ACC), Cribriform pattern (Figure 1A, B). The patient subsequently underwent resection of the tumour. We received a segment of trachea measuring 4.0cm in greatest dimension. The luminal surface showed a polypoid ulcerated mass measuring 1.5 cm in greatest dimension. The histopathologic sections showed features of Adenoid Cystic Carcinoma, Cribriform type. Solid component comprised less than 5% of the total tumour. The dis-