Proposal for an ICD‑10‑CM Code: Pseudologia Fantastica

 Proposed title: Pseudologia fantastica (pathological lying)

Proposed placement: Chapter 5, Mental, Behavioral and Neurodevelopmental Disorders; category F68, Other disorders of adult personality and behavior
Proposed code: F68.8X — Pseudologia fantastica
The final alphanumeric code should be assigned by CDC/NCHS and CMS to preserve ICD‑10‑CM hierarchy.

Requested action

Create a distinct ICD‑10‑CM diagnosis code for pseudologia fantastica, also termed pathological lying, defined as a persistent pattern of elaborate, recurrent falsification that is disproportionate to, or not adequately explained by, clear external gain; is not better accounted for by psychosis, delirium, neurocognitive disorder, intoxication, or ordinary situational deception; and causes clinically significant impairment, risk, or treatment interference.

Rationale

Clinicians regularly encounter patients who repeatedly present dramatic, internally inconsistent, or fabricated personal histories. The pattern may disrupt treatment, create needless emergency evaluations, damage family relationships, lead to inappropriate prescribing or hospitalization, and undermine continuity of care.

Current ICD‑10‑CM choices do not accurately capture this presentation:

• Z76.5, Malingerer [conscious simulation] implies deliberate deception for a recognizable external incentive, such as money, avoiding legal consequences, drugs, housing, or other tangible benefit.

• Factitious disorder imposed on self concerns intentional falsification or induction of illness for the sick role; it does not cover the broader pattern of chronic, fantastical fabrication across ordinary life domains.

• Psychotic disorders may involve fixed false beliefs that the patient experiences as true; pseudologia fantastica requires assessment of a pattern of fabrication rather than delusional conviction.

• Personality-disorder codes may describe co-occurring traits but do not identify the clinically central behavior or permit useful tracking of its course and response to treatment.

A separate code would improve diagnostic precision without presuming motive, moral failure, dangerousness, or criminal intent. It would allow clinicians to document the condition honestly while preserving appropriate differential diagnosis and avoiding inaccurate use of “malingering” or “factitious disorder.”

Proposed diagnostic guidance

Pseudologia fantastica may be coded when all of the following are present:

1. A persistent or recurrent pattern of extensive fabrication or exaggeration of personal experiences, history, symptoms, achievements, relationships, or identity;

2. The accounts are often dramatic, shifting, or implausible, and may contain partial truths;

3. The behavior is not primarily explained by a clear external reward, by feigned illness for the sick role, or by a psychotic or neurocognitive process;

4. The pattern causes clinically significant impairment, risk, relational disruption, unnecessary utilization, or substantial interference with evaluation or treatment; and

5. The diagnosis is made cautiously after collateral review when feasible and after considering trauma-related conditions, dissociation, substance effects, developmental disorders, personality disorders, factitious disorder, malingering, and psychosis.

Recommended coding notes

Excludes1:

• Malingering (Z76.5)

• Factitious disorder imposed on self or another

• Delusional disorder and other psychotic disorders

• Delirium, major neurocognitive disorder, and substance-induced conditions

Code also:

• Any co-occurring personality disorder, trauma-related disorder, substance-use disorder, mood disorder, psychotic disorder, or neurocognitive disorder, when independently established.

Benefits of adoption

A dedicated code would:

• Improve clinical documentation and handoffs;

• Reduce misuse of malingering and factitious-disorder diagnoses;

• Support research on prevalence, comorbidity, treatment, healthcare utilization, and outcomes;

• Permit better quality review of recurrent fabricated histories that cause avoidable testing or crisis care; and

• Encourage neutral, behavior-based language rather than pejorative labeling.

Safeguards

This code should not be used merely because a patient is mistaken, unreliable, disagreeable, inconsistent under stress, or unable to corroborate a history. It should not be used as a forensic conclusion absent appropriate evaluation. Documentation should identify the observed discrepancies, relevant collateral information, differential diagnosis, and the clinical consequences of the behavior.

Recommendation: Add a distinct ICD‑10‑CM code for pseudologia fantastica/pathological lying under F68, with the above inclusion and exclusion guidance.