Coexistence of tuberculosis and lung cancer is fairly rare. However, there are different estimates about the prevalence of this combination. Watanabe et al suggested that it reaches 2.1% of patients with lung cancer . This result was further confirmed by Cicėnas and Vencevičius . However, Dacosta and Kinare identified this combination in 13.1% of patients with lung cancer .
Cicėnas and Vencevičius also indicated that epidermoid carcinoma is the lung tumour which is mainly associated with tuberculosis . On the contrary, bronchial adenocarcinoma, which was the case in our patient, was diagnosed only in 21.7% of cases.
Although the association of HPOA with bronchial carcinoma and pulmonary tuberculosis is well known, the exact pathogenetic mechanism of the syndrome is still unclear. It was suggested that in cases of lung diseases, congenital cyanotic heart diseases and liver cirrhosis, megakaryocytes bypass the pulmonary circulation through arteriovenous shunting and escape fragmentation. Then, these unfragmented megakaryocytes stimulate the production of platelet derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) by endothelial cells, resulting in angiogenesis and endothelial hyperplasia which is manifested as clubbing of fingers and toes .
Summarizing, we present a rare case of HPOA due to coexistence of bronchial adenocarcinoma and pulmonary tuberculosis. The presence of a readily recognised cause of HPOA should not prevent the clinical doctor from excluding other potential coexisting pathologic conditions that could also contribute to HPOA.