Sarcoidosis or malignancy: a diagnostic dilemma.

Differentiating sarcoidosis from malignant neoplasms is not always easy. Sarcoidosis may present with bronchial stenosis and pseudotumorous formations in the lung and in various other organs. Conversely, metastatic or lymphomatous invasion of thoracic lymph nodes more often closely resembles the bilateral hilar adenopathies of sarcoidosis. Asymmetric lymph node swelling, while suggestive of malignancy, does not rule out sarcoidosis. Regional or generalised granuloma formation may occur in patients with malignant lymphoma or carcinoma of the lung, probably in reaction to neoplastic tissue. Its influence on prognosis remains obscure, but awareness of its possible presence is necessary in the diagnosis and staging of cancer. The present evidence does not indicate that sarcoidosis predisposes to malignant tumours.