DISCUSSION
HPO is an orphan syndrome (1). It can be divided to primary HPO; pachydermoperiostosis, mainly seen in children or young adults, with a genetic predisposition (3) and secondary HPO that is seen in 97% of the cases. It is mainly due to a pulmonary affection in that case called “hypertrophic pulmonary osteoarthropathy” (HPOA) (3) but also it could be secondary to a cardiac, gastric, hepatobiliary or miscellaneous cause.
The main clinical features of the syndrome are finger and toe cubbing. We can also see skin hypertrophy that may give coarse facial features or swelling at the ankles. A thickening of tubular bones had been described and it might be more noticeable in the extremities such as ankles and wrists. Periosteal effusion may also happen causing tenderness in palpation of concerned areas. In the particular case of lung cancer, patients may experience burning sensation of the fingertips and bone pain (1)
A case of HPO was described in a homeless patient with schizophrenia; it was secondary to an infectious endocarditis (4). For of our patient, HPOA was a paraneoplastic syndrome secondary to a pulmonary neoplasm.
Several studies have looked at the frequency of lung cancer in schizophrenic patients. we found a review of literature that concluded to a certain resistance of patients with schizophrenia towards cancer (5) compared to the general population. Another study conducted on patients with schizophrenia and their relatives found higher incidences of cancer in the patients compared to their relatives (6). The most frequent cancer in schizophrenia was lung cancer for men and breast cancer for women (6), but studies had controversial results when comparing the incidence of lung cancer in schizophrenia patients compared to the general population. But once the diagnosis is made, patients with schizophrenia have poorer survival rates (7) more than twice the risk of mortality (8).
This emphasizes how important is the screening of schizophrenic patients at risk of lung cancer (8) especially that the first risk factor of lung cancer is smoking (9). Tobacco consumption has been documented in schizophrenia. The patients smoke both more frequently and bigger quantities of cigarettes, throughout all the stages starting from first episode psychosis (FEP) to chronic disease (10). Many hypotheses tried to find explanation to this phenomenon; smoking is thought to have a good impact on negative symptoms, to have sedative effect or to deal with extrapyramidal symptoms (10). A genetic study even identified a shared loci between lung cancer and smoking (11). This should encourage clinicians to use different available methods to reduce or stop smoking (12) (13)