A case of diffuse hepatic metastasis of small cell bronchial carcinoma is presented. The first symptoms were specific PCT lesions and excessive excretion of urinary porphyrins. The patient was subjected to various instrumental examinations. Selective arteriography, CAT and hepatic echography showed liver to be of enormous size and completely homogeneous, suggesting a diagnosis of Budd-Chiari syndrome. Only hepatic scintigraphy showed multiple take-up lacunae and complete organ substitution. The rarity of the case and the possible pathogenesis of paraneoplastic PCT are discussed.