Case 34. (22 Jun 1998)
Diagnosis: Mucoepidermoid carcinoma,low grade
Mucoepidermoid carcinoma of the lung is an uncommon
tracheobronchial tumor whose incidence has been estimated at between 2
to 5 per 1000 primary bronchial neoplasms. The lesion is classified pathologically
into low-grade and high-grade malignancy. The majority of tumors present
as a polypoid mass in the lumen of a main or lobar bronchus. The tumor
is usually confined to the bronchial wall, although the high-grade form
may extend into the peribronchial interstitium or adjacent lung parenchyma.
Roentgenographic manifestations in 58 cases reviewed by the Armed Forces
Institute of Pathology (AFIP) consisted of a solitary nodule or mass in
41 and pneumonic consolidation" in 16. Occasionally, the appearance
is that of an endobronchial or endotracheal tumor similar to that of adenoid
cystic carcinoma. In the AFIP series, the average age of individuals with
low-grade forms was 35 years, and that of persons with high-grade forms
45 years. Symptoms are related to intraluminal growth and include cough,
hemoptysis, wheezing, and recurrent pneumonia. Low-grade mucoepidermoid
carcinoma grow slowly. Provided that they are surgically resectable, the
prognosis is usually excellent, without recurrence or the development of
metastases. Behavior of the high-grade form, although worse than that of
low-grad tumors, appears to be better than the commoner forms of pulmonary
carcinoma.
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