Fifty consecutive patients with
solitary pulmonary nodules (SPN) on chest radiographs were studied scintigraphically after the administration of a
somatostatin analog 99mTc-
EDDA/HYNIC-TOC. The activity amounted to 740-925 MBq and a single photon emission computed tomography (SPECT) technique was applied. Verification of the nodule etiology was based on histology or cytology and bacteriology. As additional criterion for nodule benignity, its stable size in a chest radiograph for at least 3 years was accepted. In 31 patients, malignant etiologies of nodules were found. The diagnoses included: 11
adenocarcinomas, 6
squamous-cell carcinomas, 2
large-cell carcinomas, 6 nonsmall-cell
lung cancers (NSCLC) of unspecified, more detailed morphology, 2 small-cell
lung cancers (SCLC), 2 typical
carcinoids, and 2 metastatic
tumors:
leiomyosarcoma and
malignant melanoma. In 19 patients, the following benign
tumors were diagnosed: 6
tuberculomas, 2 other
granulomas, 4
hamartomas, 2 nonspecific inflammatory infiltrates, 1
abscess, 1 peripheral
carcinoid of morphological characteristics of a benign
tumor, 1 ectopic lesion of thyroid tissue, and 2 benign
tumors of unspecified etiology, with stable size over 3 and 5 years. Positive scintigraphic results were obtained in 28 of 31 patients (90%) with malignant SPNs; among these there were 26 of 27 (96%) cases of primary pulmonary
carcinoma. The remaining 2 false-negative cases included metastatic
tumors:
liposarcoma and
melanoma. Among 19 benign lesions, 15 (79%) did not accumulate the
radiopharmaceutical. The remaining 4
tumors visible on scintigrams included: 1
tuberculoma, 1
hamartoma, 1
abscess, and 1 case of nonestablished diagnosis (with stable size over 3 years). In conclusion, scintigraphy with 99mTc-
EDDA/HYNIC-TOC appears to be an effective procedure for differentiation between malignant and benign SPNs.