Spherical and Ovoid Lesions of the Lung

Abstract

Interest in this subject is attested by pertinent articles in current medical journals. There seem to be valid reasons for this. These include asserted increase in clinical incidence of conditions associated with characteristic x-ray changes, and newer diagnostic methods derived from advancing technology. Also, socio-economic implications may have some role in this respect, namely recent developments illustrate that highly competent diagnostic work-up can be carried out with reasonable safety without having the patient hospitalized. Reports of the 1950s indicated an incidence of 1 to 2 percent of solitary round pulmonary nodules on mass chest x-ray surveys. The typical round or oval x-ray shadow does not in itself identify its underlying pathologic substrate or etiology. Small areas of calcifications in these lesions usually rule out malignant neoplasm, except when the latter develops near the hilar region where it may engulf preexisting small calcified foci. London and Winter reported an unusual case of peripheral solitary round lesion caused by adenocarcinoma of the lung with psammamatous calcifications (Arch Int Med 94:161, 1954). Mass x-ray surveys, with follow-up examinations, revealed that less than 5 percent of these shadows connoted malignant tumor. In contrast, it is well to remember that in a large group of collated clinical cases, malignant lung tumor (primary or metastatic), was observed in 40 percent, with a variety of nonmalignant lesions in 60 percent. The latter comprises a rather high number of granlomatous lesions caused by Histoplasma capsulatum, Coccidioides immitis, other fungi, tubercle bacilli and a small number of pathologic entities due to other causes. Spherical and ovoid lesions may be caused by a great variety of diseases. Among these are benign tumors, such as myoma, hamartoma, chemodectoma, neurofibroma, hibernoma and chondroma. Adult type of chondroma has been listed, according to its composition, under various names, such as chondrohamartoma, chondroadenoma, adenolipofibro osteochondroma, lipochendroadenoma and bronchoma. Weinberger et al aptly comment that although adult type of harmartoma is considered by many experts a late-appearing developmental anomaly, its histogenetic and behavioral characteristics are similar to those of a benign acquired tumor (Ann Thorac Surg 15:67, 1973). Viereck found 60 percent of bronchial adenomas as “coin lesions” (Chirurg 4:309, 1970). There are other entities which may cast round or oval shadow: vascular anomalies (arteriovenous fistula, pulmonary venous varicosities, capillary hemangioma, sclerosing hemangioma, anomalous single left pulmonary vein, aneurysm of an intercostal artery), some instances of Loeffler's syndrome (of parasitic, bacterial, pollen or medicinal origin), ornithosis, primary amyloidosis, gumma, small ectopia of some of the abdominal organs, abscess, infarction, subpleural intrapulmonary lymph node, plasmacytoma and xanthomatous lung lesions. Plasmacytoma may remain histologically and clinically nonmalignant or, for reasons unknown, may assume the characteristics of malignant neoplasm. Spherical lung lesion may be a sequel of nonpenetrating trauma. Interlobar transudate in the horizontal fissure of patients with congestive heart failure may be visualized as a round or oval x-ray shadow (“vanishing” or “evanescent chest tumor”). In the differential diagnosis, it is mandatory to exclude nonpulmonary diseases which may be associated with round or oval shadows in chest x-rays. The seemingly puzzling diagnostic enigma of spherical and ovoid lung lesions can be resolved by due attention to medical history of the patient, possible paraneoplastic symptoms and signs, detection and examination of sentinel lymph nodes, specific laboratory studies, including cytologic examinations, special x-ray work-up, determination of the rate of growth of the lesion, fiberoptic bronchoscopy (biopsy and bronchial brushing), transcutaneous needle biopsy, and exploratory thoracotomy. Availability of modern instruments reduces incidental diagnostic hazards to a minimum and thus permits an aggressive therapeutic attitude. Prompt and accurate diagnosis assures optimal treatment.