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)