A 41 - year - old woman presented with a history of aches and pains all over the body and generalized weakness for four years. She cannot sleep because of the illness and has lost her appetite as well. She has lack of interest in work and doesn't like to meet friends and relatives. She denies feelings of sadness. Her most likely diagnosis is:

In this case, patient has significant somatic symptoms such as aches and pain and generalized weakness. In a large number of patients, depression presents mostly with somatic complaints and patient may deny psychological symptoms such as sadness of mood. Fuher, in this patient there are sleep and appetite abnormalities along with loss of interest which clinches the diagnosis of depression.