Histoplasmosis skin test
CPT code 86510 covers the histoplasmosis skin test, a diagnostic procedure where a small amount of histoplasmin antigen is injected under the skin to check for immune response to the Histoplasma fungus. The test helps determine if someone has been exposed to or infected with histoplasmosis, a fungal infection common in certain geographic regions.
This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.
RVU breakdown
Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High
NCCI bundling edits
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Billing tips
Verify histoplasmin antigen availability before scheduling; the test has limited commercial availability and Medicare may deny if antigen is not FDA-approved or commercially available
Impact: Prevents 100% payment loss ($7.44) and wasted clinical time on unbillable procedures
Bill the interpretation and reading separately from administration if performed; document the 48-72 hour follow-up reading with specific induration measurements in millimeters
Impact: Ensures complete reimbursement for all components of service; missing documentation can trigger $7.44 denial
Include ICD-10 codes that demonstrate medical necessity such as B39.x (histoplasmosis variants), Z20.7 (contact with and exposure to pediculosis, acariasis and other infestations), or Z87.01 (personal history of tuberculosis) for endemic exposure evaluation
Impact: Improves first-pass acceptance rate by 40-60%; reduces medical necessity denials
When billing with same-day E/M service, append modifier 25 to the E/M code (not to 86510) and ensure documentation shows the E/M was separately identifiable and above routine test administration
Impact: Protects E/M payment of $50-$300; incorrect modifier placement results in denial of higher-value service
Consider that many payers classify 86510 as 'not separately payable' or 'limited coverage'; verify individual payer policies before performing test
Impact: Prevents write-offs; some commercial payers may pay $0 regardless of medical necessity
Document geographic exposure history and specific clinical indication; generic 'screening' indications will be denied as not medically necessary
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