The problem with misidentifying an angry person as depressed is that the treatment for clinical depression is not benign.
The drugs used to treat depression can interact with other drugs, can lead to symptoms (side effects) of their own, and are not inexpensive. More importantly, antidepressants are not a solution to anger.
Aggravating a patient whose pain complaints are minimized may result in a constellation of symptoms that at once appear to be both anger and depression. Being in pain often results in dependency upon whomever can provide relief.
This reliance upon others is sometimes referred to as “hostile dependency.” Interestingly, this is also seen in teenagers who seek to, but cannot really afford to, be independent.
So, let us assume that the patient is quite angry. In both depression and anger, the individual is sullen, often withdrawn and brooding, restless and agitated, and likely no one wants to listen to what seems like endless complaining.
Whether a clinician or counselor, someone needs to spend time differentiating (and helping the patient separate) between anger and depression. Anger can be resolved with reassurance that amends will now be made. Depression, by contrast, requires treatment.