Case
26. (27 Apr. 1998)
Diagnosis: Endobronchial Hamartoma
Hamartoma can be defined as a developmental malformation
composed of tissues that normally constitute the organ in which the tumor
occurs, but in which the tissue elements, although mature, are disorganized.
In the lung, the term traditionally refers to a well-circumscribed tumor
consisting predominantly of cartilarge and adipose tissue. In recent years,
several authors have proposed that they are best regarded as benign neoplasms,
probably derived from an undifferentiated bronchial wall mesenchymal cell.
Hamartomas are uncommon pulmonary neoplasms (5.7%
of 2958 solitary lung lesions). Most are discovered in adulthood, with
a peak incidence in the sixth decade. The tumors occur most often in males
(2~3 times). Approximately 90% of pulmonary hamartomas are located within
the parenchyma, usually in a peripheral location. Endobronchial hamartoma
is a special form of the usual intrapulmonary hamartoma, which originates
from a large bronchus, grows into the lumen, and obstructs the bronchi
before it grows big. Most endobronchial tumors, therefore, produce symptoms,
such as cough and fever, due to bronchial obstruction.
Endobronchial hamartomas most often appear as fleshy,
polypoid tumors attached to the bronchial wall by a narrow stalk. The central
portion is usually composed of a core of adipose tissue surrounded by somewhat
compressed loose fibrous tissue. Smooth muscle, seromucinous glands, and
myxomatous tissue may be admixed. Cartilage is often absent or present
in small amounts. In a small percentage of cases, bronchial obstruction
leads to atelectasis, obstructive pneumonitis, and progressive peripheral
lung destruction. Whenever a fatty endobronchial mass is identified on
CT scans, the differential diagnosis should be narrowed to lipoma and hamartoma.
Return to Case 26. (27 Apr.
1998)