F21 — Schizotypal disorder

Concept, in one sentence

A stable, long-standing pattern of eccentric thinking, perception, speech and relating, related to schizophrenia but without a sustained psychotic episode.

Decisive boundary cues

• Stable pattern since adolescence, no sustained episode -> weighs toward F21 over F20.
• One fixed, elaborated delusion with otherwise unremarkable speech/affect -> weighs toward F22 over F21.
• A clear new change from baseline lasting >= 1 month with broad disturbance -> weighs toward F20 over F21.

Duration/course cue

No minimum-duration threshold; the key question is stability/onset, not length of a discrete episode.

Nearest alternatives

F20, F22

Common mistake

Assuming lifelong eccentricity rules out a new psychotic episode, or conversely, mistaking a stable lifelong pattern for an active illness.

Retrieval prompt — one-line memory anchor

Has this always been the person's pattern, or is it new?