Hamartoma: On Occasion a Rapidly Growing Tumor of the Lung

Hamartomas of the lung occur principally in the peripheral pulmonary parenchyma, usually presenting as a solitary pulmonary lesion on a routine chest roentgenogram in an asymptomatic patient. They constitute about 8 per cent of the so-called “coin” lesions of the lung, following carcinoma and granuloma in incidence. While it was originally thought that hamartomas were characterized by a lack of change in size and shape for several years, recent studies have shown that they may grow, although in a slow and regular fashion (3–7). Articles have stated that growth, which is at a maximum of 5 mm in diameter per year, could be detected with certainty only on roentgenograms taken several years apart (8, 9). A review of the literature led to the detection of only one case of a rapidly growing hamartoma, but this aspect was not discussed (10). The purpose of this paper is to show not only that hamartomas of the lung may grow, but also that they may do so rapidly. I. B., a 13-year-old white female who was treated for primary tuberculosis of the right upper lobe at the age of two years, was being followed with yearly chest roentgenograms to detect any reactivation. In February 1965 the only abnormalities seen were some calcified nodular densities in the right upper lobe and upper portion of the right hilus which were consistent with old, healed tuberculosis (Fig. 1). Exactly one year later, a new, 1.0 X 1.0-cm round density was noted in the right lower lung field (Fig. 2). Thirteen months later, in March 1967, the mass had increased markedly in size, to 2.3 X 3.4 cm in diameter (Fig. 3). The patient was asymptomatic, and no abnormal physical or laboratory findings were detected. Laminagrams failed to reveal any calcification within the mass. The possibilities considered in the differential diagnosis were tuberculoma, metastatic tumor, lymphoma, bronchial adenoma, hamartoma, bronchocele, and granuloma of nontuberculous etiology. The patient was placed on a six-week course of antituberculous therapy, but the lesion nevertheless continued to grow, measuring 2.6 X 2.6 X 3.8 cm in diameter on radiographs obtained in June 1967 (Fig. 4). Shortly thereafter she underwent exploratory thoracotomy. A 2.5 X 2.5 X 3.5-cm, well encapsulated, firm white tumor was easily enucleated. Histologically, it proved to be a typical benign hamartoma. Discussion A lung tumor which grows rapidly while under observation is usually regarded as malignant. This report emphasizes that rapid growth does not exclude a benign hamartoma from consideration. Another point worth emphasizing is that none of the previously reported cases of hamartomas which have grown under observation, including the present case, have shown either clinical or histologic evidence of malignancy (4, 5, 8).