Cluster A and C personality — differentials and stepped management (MEQ)

(i) Working diagnosis and differentials. Working diagnosis: avoidant personality disorder (social inhibition, feelings of inadequacy, hypersensitivity to negative evaluation, desire for connection with avoidance of risk) with clinically significant perfectionism that may meet OCPD features or trait anankastia. Key differentials with discriminators: social anxiety disorder (often co-occurs/continuum — may be more performance-bound; still diagnose AVPD when pervasive self-concept and life constriction meet criteria); schizoid PD (low desire for relationships vs desire present here); schizotypal PD (no magical thinking/odd speech/ideas of reference described); autism spectrum (sister reports no early language delay; still screen social communication/sensory profile carefully — dual formulation possible); depression secondary to isolation; OCD if true ego-dystonic rituals emerge beyond perfectionistic rewriting.[1][3][4]

(ii) Assessment priorities. Longitudinal history from adolescence; collateral; MSE (anxious affect, self-deprecation, absence of psychosis); structured screens for SAD, depression, OCD, ASD as indicated; substance use; occupational function; suicide risk (isolation + possible depression elevates risk — ideation, intent, plan, means, protective factors); capacity for treatment decisions; goals for therapy. Baseline investigations if medication considered or atypical features (TSH, routine bloods, UDS as indicated).[1][3]

(iii) Psychological plan. Psychoeducation that AVPD is treatable. Offer CBT with graded exposure hierarchy (emails → brief meeting comments → social activities), cognitive restructuring of inadequacy/rejection beliefs, behavioural experiments, and social skills practice. If broader lifelong schemas and multi-domain rigidity dominate, schema therapy has RCT support in mixed PD samples (Bamelis 2014). Set session structure, homework, and collaborative measurement of avoidance. Address perfectionism with “good enough” experiments. Involve workplace graded return if appropriate.[1][2]

(iv) Pharmacotherapy principles and example. No drug treats AVPD as a whole. Treat comorbidity. Example: if comorbid social anxiety/depression warrants medication, sertraline 50 mg orally once daily, review 1–2 weeks for activation and suicidality, titrate toward 50–150 mg as tolerated with a response review plan — this treats anxiety/depression, not personality identity. Avoid chronic benzodiazepines for avoidance. Stop/review dates mandatory.[1]

(v) ICD-11 sentence. ICD-11 rates personality disorder by severity (mild/moderate/severe) and qualifies with trait domains (here negative affectivity and detachment ± anankastia) rather than requiring a DSM Cluster C label.[5]