Aleukemic leukemia presenting with paranoid psychosis.

Mast cells not only synthesize and release serotonin, but also express and are activated through multiple serotonin receptors. Low blood serotonin level might define a specific subset of patients with systemic mastocytosis (SM) who are more likely to present with neurologic and gastrointestinal complaints. Mast cell leukemia (MCL) is a rare and aggressive type of systemic mastocytosis, and psychiatric manifestations in its course have not been well-characterized.