Pathology/Lab Coding Alert

Microscopic examination of pathology tissue specimens often involves the use of special stains. To appropriately capture reimbursement for these services, pathology coders need to be familiar with these stains as well as the specialized rules for reporting them.

Some stains are not separately reportable but are considered bundled with the standard tissue and slide preparation involved in the specimen evaluation, says R.M. Stainton Jr., MD, president of Doctors Anatomic Pathology Services, an independent pathology laboratory in Jonesboro, Ark. Other stains are reported in addition to the primary pathology service, as indicated by their CPT designation as add-on codes (represented by a + sign preceding the code). And other special stains are coded in addition to the primary service, although CPT does not designate them as add-on codes.

The most generally useful and commonly applied stain for microscopic tissue examination is hematoxylin and eosin (H&E), Stainton says. Any of the surgical pathology services that describe microscopic tissue examination will incorporate the H&E stain. This includes listed and unlisted tissue specimens from adrenal gland to vein, reported with 88302-88309 (levels II to VI - surgical pathology, gross and microscopic examination).

Depending on the tissue and the disease process being investigated, the pathologist may use a wide variety of special stains to further elucidate the diagnosis, Stainton says. These tissue stains fall into four main codes:

1. Code +CPT 88312 (special stains [list separately in addition to code for surgical pathology examination]; group I for microorganisms [e.g., Gridley, acid fast, methenamine silver], each);

2. Code +88313 (... group II, all other, [e.g., iron trichrome], except immunocytochemistry and immunoperoxidase stains, each);

3. Code 88314 (... histochemical staining with frozen section[s]); and

4. Code 88342 (immunocytochemistry [including tissue immunoperoxidase], each antibody).

To help coders recognize and assign the correct code for stains they may encounter in narrative documentation of surgical pathology examinations, Stainton describes some of the most commonly used stains:

1. Stains Under 88312

Acid Fast Stain: Almost any time a pathologist observes granulomas in a tissue biopsy, an acid fast stain is ordered. This stain is crucial for the identification of acid-fast bacilli involved in diseases such as tuberculosis (e.g., 010.0x, primary tuberculous infection). For example, if a pathologist examines a transbronchial biopsy of the lung (88305) and notes granulomas, he or she would most likely order an acid fast stain, which could lead to the treatment of this curable disease.

Methenamine Silver, Periodic Acid Shift (PAS), Gridley Stain: These and similar stains are used for the identification of fungi in tissue samples. These stains may be ordered in suspected cases of histoplasmosis (115.xx), blastomycosis (116.x, blastomycotic infection) or coccidioidomycosis (114.x).

Brown Brenn: Brown Brenn is a tissue gram staining technique. It provides a method for differential staining of gram-negative and gram-positive bacteria in tissue sections. This aids in the diagnosis of disease-causing organisms.

Steiner Stain: Steiner Stain is commonly used for the identification of Helicobacter pylori. The stain will often be carried out on gastric biopsy material for the diagnosis of Helicobacter gastritis.

2. Stains Under 88313

Iron Stain: Iron stain is most commonly used for bone marrow aspirate (85095, bone marrow; aspiration only) samples. Although it may also be carried out for bone marrow biopsy specimens (85102, bone marrow biopsy, needle or trocar), these typically require decalcification (88311, decalcification procedure [list separately in addition to code for surgical pathology examination]) first, and the specimen may not stain as well as the aspirate. The stain is used to evaluate iron stores in the bone marrow, especially for the diagnosis of iron deficiency anemia (280.x, iron deficiency anemias) and other iron metabolism disorders. Note that 88313 involves physician evaluation and is not appropriate for other iron stains that are more often performed by a medical technologist and reported without physician interpretation. The following codes are used in those instances.

Although 88313 describes iron stains for bone marrow or other tissue, new code 85536 (iron stain, peripheral blood) should be used to report iron stains for peripheral blood. A note in the CPT manual directs coders, For iron stains on bone marrow or other tissues with physician evaluation, use 88313. Code 85535 (iron stain [RBC or bone marrow smears]) reports yet another type of iron stain, which evaluates for sideroblastic or reticuloendothelial bone marrow stores.

Trichrome Stain: Three contrasting colors are used in this tissue dye technique to highlight connective tissue, muscle, cytoplasm and nuclei. This is often used, for example, for a liver biopsy (88307) when fibrosis is observed. A reticulum stain would also typically be ordered, which would be coded as a second 88313. These stains are often used in the diagnosis of hepatitis and cirrhosis of the liver (571.x, chronic liver disease and cirrhosis).

Congo Red Stain for Amyloid: This stain is commonly used in the diagnosis of tumors and other disorders associated with amyloid deposits such as paraganglioma, for example, tumor in the carotid body (237.3, neoplasm of uncertain behavior of paraganglia).

Elastic Stain: May be used to elucidate arterial elasticity for the diagnosis of conditions such as temporal arteritis (446.5, giant cell arteritis).

Giemsa Stain: A compound of methylene blue-eosin and methylene blue, this stain is used to demonstrate spirochetes and protozoans in tissue samples, as well as aid in the diagnosis of rabies. It is also used for the differential staining of blood smears (85060, blood smear, peripheral, interpretation by physician with written report).

Other common stains reported using 88313 include mucin, melanin, and methyl green-pyronin.

3. Stains Under 88314

We use this code to report histochemical stains on muscle tissue, reports Elizabeth Sheppard, HT (ASCP), manager of anatomic pathology at Wake Forest University Baptist Medical Center in Winston Salem, N.C. The stain is used in the diagnosis of atrophy or dystrophy muscle conditions, such as muscular dystrophy (359.1, hereditary progressive muscular dystrophy). Histochemical stains such as ATPase and NADH cannot be conducted on routinely processed (paraffin block) muscle tissue. It must be cut frozen, Sheppard says. Typically the muscle biopsy is submitted, ATPase stain and NADH are ordered, meaning that 88314 x 2 would be reported. However, if the muscle biopsy is also submitted for paraffin processing and H&E stain, 88305 would be reported as well.

4. Stains Under 88342

Immunoperoxidase: Various, specialized immunoperoxidase stains identify a multitude of solid tumors by acting as a marker for specific tumor antigens. Some of the common stains include keratin, S100, HMB45, NK1 and C3. There is a whole host of these stains, and more are being created all the time as new tumor markers are identified.

These solid tumor markers act by reacting a specific antibody with the tissue sample. If the stain takes, it indicates the presence of a specific protein that is used to identify the type of tumor. This identification is crucial for determining the most appropriate course of treatment for a tumor.

Stainton also points out that because these stains often represent a process of elimination, multiple immunoperoxidase stains with different antibodies may be used on a single tissue specimen. That is why the code-specific immunoperoxidase stain is used.

Remember that immunoperoxidase is a tissue stain, used to identify solid tumor markers. It is different from tumor markers, reported with codes such as 86294-86304 (immunoassay for tumor antigen) and 86316 (... other antigen, quantitative [e.g., CA 50, 72-4, 549], each), which are used to classify cancers from blood samples.

Keratin (cytokeratin): Keratins are a group of individually identified proteins present in epithelial cells specific to certain tissue types. As such, antibodies to keratin proteins are commonly used as a stain for histologic typing of tumors. Keratin stains are especially helpful in distinguishing between carcinomas, sarcomas, lymphomas and melanomas.

Other Immunocytochemistry Stains: These include some of the older stains that were often used on bone marrow aspirates to differentiate the types of leukemia. These include esterase, Sudan black B, and myeloperoxidase.

Billing Units

Whether using the add-on codes (+88312, +88313) or other special stain codes, the basic principle for reporting the service is the same. Pathologists should report special stains in addition to the primary pathology service.

Because the specimen is the unit of service for surgical pathology, report a special stain used for tissue analysis once per specimen, regardless of the number of slides prepared and evaluated. This has been a bone of contention for those conducting sentinel lymph node biopsies (88307), because they conduct numerous stains in the search for occult metastases. The sentinel lymph node protocol calls for the preparation of multiple paraffin blocks from the lymph node. Each block is then sectioned, and slides examined. If carcinoma is not identified, keratin stains are conducted for multiple tissue sections to identify possible micrometastases. This may result in many keratin stains from one lymph node, but 88342 can be reported only once because the slides are all from a single specimen.

Finally, pathologists should report each special stain separately. So if multiple special stains are carried out on a single tissue specimen, each stain is reported once. Note that this is true whether the CPT code for two different stains is the same or different. In other words, if two different stains that use the same code (e.g., acid fast bacillus [88312] and methenamine silver [88312]) were used on the same specimen, you would report 88312 x 2. This principle explains why 88342 reads each antibody. Each antibody effectively represents a separate stain. So multiple units of 88342 could be reported for the same specimen depending on how many separate antibodies were tested.

Capturing reimbursement for special stains involves a few simple steps. First, be familiar with which stains are reported using which code. Then, report the stain code in addition to the primary pathology service code. Remember to report multiple stains if more than one special stain is carried out, but report each stain only once per specimen, regardless of the number of slides involved.