Cylindroma, Carcinoid Tumors, and Mucoepidermoid Carcinoma

Abstract

The three types of neoplasm discussed here were classified in the past under the benign appellation of "adenoma." This was misleading and inappropriate because cylindroma, carcinoid tumor, and mucoepidermoid carcinoma are true malignancies with full potential for local invasion and systemic dissemination. There is no known risk factor or gender predilection. The similarity stops here. They differ significantly from each other and from bronchogenic carcinoma in many ways and can be a challenge to all physicians involved, whether it is the pulmonologist, thoracic surgeon, pathologist, or medical oncologist. CYLINDROMACylindroma or adenoid cystic carcinoma is a low-grade malignancy. In addition to the lung and airway, it has been described in the salivary gland, breast, skin, cervix, esophagus, and prostate. 1 It can also arise rarely in mucous glands of the palate, maxillary sinus, eustachian tubes, and the external auditory canal. 2 Cylindromas account for 5 to 10% of patients with bronchial tumors of mucous gland origin 1,3 and ranks second in frequency to carcinoid tumors. Peak age of incidence is in the fourth and fifth decade. 24 Children are rarely affected.Cylindroma usually arises centrally, in the trachea or main stem bronchi and accounts for up to 40% of all major airway tumors. 13 In the trachea, the tumor is usually found in the middle third, 2 , posterolaterally in the angle formed by the cartilaginous rings and the membranous wall where mucous glands are numerous. Less than 10% of cylindromas will present as a solitary pulmonary nodule 5 and it is impossible to distinguish histologically a primary lesion from a lung metastasis. Goldstraw and colleagues noted a predilection for the right side in primary pulmonary cylindroma, a finding confirmed by others. 67 CLINICAL PRESENTATIONObstructive symptoms are common and include dyspnea, wheezing, cough, and recurrent episodes of pneumonia. 7 Dyspnea and wheezing are the most common presenting symptoms. 2 ' 8 In a series of 38 patients collected over a 20-year period, Grillo et al. noted that dyspnea was present in 69% and hemoptysis in 28%. 9 In a report of 38 patients collected over a 32-year period, Maziak and coworkers observed wheezing, cough, and stridor in 39%, 23%, and 21% of their patients, respectively. 8 The slow growth rate can occasionally account for a significant time interval between the onset of symptoms and the actual diagnosis. Goldstraw reported a mean time interval of 50 months between the onset of symptoms and diagnosis. 10 PATHOLOGY It is postulated that cylindroma arises in the collecting duct-acinar region of the bronchial glands since both myoepithelial cells and lining (secretory) cells are present in this location. 11,12 The polypoid or annular solid mass presents a white or Section of General Thoracic Surgery, Mayo Clinic and Foundation, Rochester, Minnesota