La belle indifférence refers to a patient’s seeming lack of concern in the presence of serious symptoms. This was first defined in the context of "hysteria", along with exaggerated emotional reactions, what might now be termed functional or somatoform illness. However, the sign is a poor discrimator against "organic" illness. Some patients’ coping style is to make light of serious symptoms; they might be labeled stoical.
Patients with neuropathological lesions may also demonstrate a lack of concern for their disabilities, either due to a disorder of body schema (anosodiaphoria) or due to incongruence of mood (typically in frontal lobe syndromes, sometimes seen in multiple sclerosis).
Stone J, Zeman A, Sharpe M. Functional weakness and sensory disturbance. Journal of Neurology, Neurosurgery and Psychiatry 2002; 73: 241-245