Calcification in pulmonary metastases.

A large variety of neoplasms can produce calcified lung metastases. Three unusual examples are presented and the relevant literature is reviewed. Each case involves a neoplasm not previously reported to produce calcified lung metastases: malignant mesenchymoma, fibrosarcoma of the breast, and medullary carcinoma of the thyroid. The sarcomas are reported in the literature to develop calcified lung metastases are osteogenic sarcoma, chondrosarcoma, synovial sarcoma, and giant cell tumour. Among carcinomas, the papillary and mucinous adenocarcinomas are the histological types most likely to develop calcified lung metastases. The metastases of a number of other tumours have calcified after antineoplastic therapy. Calcification in metastases arises through a variety of mechanisms: bone formation in tumour osteoid, calcification and ossification of tumour cartilage, dystrophic calcification and ossification of tumour cartilage, dystrophic calcification and mucoid calcification. Since calcified lung metastases can strongly resemble granulomas or hamartomas, a reasonable suspicion of malignancy is necessary when evaluating calcified pulmonary nodules.