Pathology Billing Services

Pathology billing starts with a simple question: who did the work, and where? A single specimen can involve a technical component (preparing slides) and a professional component (the pathologist's reading). Different parties may own each part, and the claim has to reflect that split.

Add special stains, immunohistochemistry (IHC, tests that use antibodies to mark tissue), frozen sections, and cytology, and a routine case can carry several line items. Units, specimen counts, and medical necessity all matter. Good pathology billing depends on clean requisitions and clear documentation from the lab. Westmont connects pathology groups, hospital-based pathologists, and independent labs with vetted billing experts who work with these rules every day.

Who this is for

• Independent pathology groups and anatomic pathology labs
• Hospital-based pathologists billing professional services
• Dermatopathology and GI pathology practices
• Cytopathology services and fine-needle aspiration (FNA) programs
• Small groups that need help with payer enrollment and denial follow-up
• Practices that send out technical work and bill only the professional reading

What gets billed

• Surgical pathology gross and microscopic exams at different complexity levels
• Biopsy and resection specimen examination
• Special stains on tissue and cytology specimens
• Immunohistochemistry, including additional stains on the same block
• Frozen section consultation during surgery
• Fine-needle aspiration adequacy checks and interpretation
• Cytology smears and concentration preparations
• Morphometric analysis of tissue stains
• Consultations on outside slides
• Professional-only (26) and technical-only (TC) billing for shared arrangements

Commonly billed codes

Code	Type	What it covers
88305	CPT	Tissue exam at a mid-level complexity, common for many biopsies
88307	CPT	Tissue exam at a higher complexity level, such as many resections
88312	CPT	Special stain for microorganisms, per group of stains
88313	CPT	Special stain for other tissue elements, per group of stains
88342	CPT	First IHC or related stain on a specimen
88341	CPT	Add-on for each additional IHC stain on the same specimen
88331	CPT	Frozen section during a procedure, first tissue block
88172	CPT	Immediate on-site review of an FNA sample for adequacy
88173	CPT	Interpretation and report of an FNA specimen
88360	CPT	Manually measured tumor marker stain analysis
D12.6	ICD-10-CM	Benign growth of the colon, unspecified site
C44.91	ICD-10-CM	Basal cell skin cancer, unspecified site

Note

Codes are examples for orientation, not a complete list, and do not guarantee coverage or payment. Always check current code sets and payer policy.

Billing challenges in pathology

• Technical and professional split. Hospitals, labs, and pathologists often share a case. Modifiers 26 and TC must match who performed each part. A biller experienced in pathology confirms the arrangement before the first claim goes out.
• Specimen counting. Each separately identified specimen may support its own exam code. Incorrect counts lead to denials or overpayments. Billers reconcile the requisition, the accession log, and the report.
• Special stain and IHC units. Stains are billed per stain or per group, and some payers limit units per case. Billers check medical necessity and note why each stain was ordered.
• Direct-to-patient and client billing. Some labs bill the referring practice, some bill insurance. Rules vary by payer and state. Billers set up the correct payer path for each client account.
• Missing diagnosis information. Pathologists often do not see the patient. If the requisition lacks a clear diagnosis, claims stall. Billers set up a process to request missing details from the ordering office.
• Frozen section and consult rules. These need clear documentation of the request and the report. Billers review notes so the service is supported if audited.
• Cytology and FNA bundling. Adequacy checks and final interpretations follow payer-specific rules. Billers track edits and appeal when the documentation supports separate payment.

How Westmont can help

• Match your group or lab with vetted pathology billing experts
• Support end-to-end revenue cycle work, from requisition intake to payment posting
• Help with denial management and appeals tied to stains, units, and medical necessity
• Assist with payer enrollment and credentialing for pathologists and labs
• Review your technical and professional billing setup for gaps

Frequently asked questions

How is pathology billing different from other specialty billing?

Pathologists usually do not see patients, so the order and diagnosis come from another practice. Claims often split into technical and professional parts, and one case can have many line items. A pathology billing company needs to manage requisitions, specimen counts, and client accounts in addition to standard claim work.

What do modifiers 26 and TC mean in pathology?

Modifier 26 marks the professional component, which is the pathologist's interpretation. Modifier TC marks the technical component, which covers equipment, supplies, and staff time. If one entity does both, many payers expect a global claim with no modifier. Check each payer's rules, since arrangements and edits differ.

Why are special stain and IHC claims denied so often?

Common reasons include too many units for the case, missing medical necessity, or stains that seem unrelated to the diagnosis. Payers may also bundle stains under frontline edits. A biller can track denial patterns, request clearer documentation from the pathologist, and appeal when the record supports the stain.

Can a pathology group bill for tests it sends to another lab?

It depends on payer rules, the type of service, and any applicable Medicare rules on referred work. Some payers require the performing lab to bill directly. Review your contracts and the payer policies, and have a billing expert confirm the correct approach before billing.

Do you need a certain software setup for pathology billing?

Most labs use a lab information system tied to a billing platform so accessions flow into charges. The exact setup varies. A billing expert can work with your current system or recommend changes that cut manual entry and errors.

Related billing services

• Clinical & Reference Laboratory Billing
• Toxicology Lab Billing
• Dermatology Billing
• Gastroenterology Billing
• Mohs Surgery Billing
• Radiology Billing