Pathology particulars

Cracking the Code

Alexander Miller

Dr. Miller, who is in private practice in Yorba Linda, California, represents the American Academy of Dermatology on the AMA-CPT Advisory Committee.

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You submit a Mohs surgical excision specimen of a basal cell carcinoma on the nose for processing by your technician. As your goal is to most effectively distinguish benign adnexal structures, including basaloid follicular proliferation, from the basal cell carcinoma, you request that in addition to the routine hematoxylin and eosin stain your technician generate slides stained with toluidine blue. You then bill 17311 for the first stage of Mohs surgery and 88314 for the additional special histochemical stain. Is that appropriate?

The CPT specifies, both in the Mohs surgery and pathology coding sections, that Mohs surgery includes staining with a routine stain including hematoxylin and eosin and toluidine blue. Consequently, only 17311 is billable in the above scenario. When a different histochemical stain — for example, a trichrome stain — is used in Mohs surgery, CPT 88314, “histochemical stain on frozen tissue block,” may be billed to code for the additional stain done. The 59 modifier should be appended to the 88314 code, specifying that a distinct staining procedure from that included in the Mohs procedure was done. Code 88314 is reported for each frozen tissue special stain done, and once per each block of tissue stained. Thus, if there are several frozen tissue blocks stained with a special stain, 88314-59 would be billed once per each block. For example, if there are four Mohs tissue blocks stained with a trichrome stain, one would bill CPT 88314-59 x4 units. For Mohs surgery, a tissue block is defined in the CPT as “an individual tissue piece embedded in a mounting medium for sectioning.” 

One may also request an immunoperoxidase stain, such as melan-A (MART-1), to be done during the course of Mohs surgery. This non-routine stain would be coded as CPT 88342 with a 59 modifier to specify the distinct, separately identifiable service. The 2014 CPT has revised the 88342 immunohistochemistry code language to include immunocytochemistry in the code definition. Additionally, the unit of service has been clarified. Previously, the unit of service was “each antibody.” For 2014, the CPT definition reads: “Immunohistochemistry or immunocytochemistry, each separately identifiable antibody per block, cytologic preparation, or hematologic smear; first separately identifiable antibody per slide.” If more than one antibody is applied to a single slide, a new add-on CPT code, 88343, is used to specify each additional distinct antibody applied to that slide. Unlike the 88314 special histochemical stain CPT code, which pertains only to frozen section tissue, immunohistochemistry CPT codes 88342 and 88343 are used for both frozen and paraffin fixed tissue slide material immunoperoxidase staining. [pagebreak]

Special histochemical stains done on formalin-fixed tissue are coded with CPT 88312 and 88313. CPT 88312 pertains to stains done typically when searching for microorganisms. Such stains include Fite, methenamine silver, and Warthin Starry. CPT 88313 codes for all other special histochemical stains such as trichrome, iron, toluidine blue, alcian blue, and PAS. The unit of service for each of these CPT codes is the surgical pathology block.

Example 1: During the course of a Mohs surgery requiring three stages of tissue excision, with two tissue blocks in the first stage and one tissue block in the second and third stage, you request one special histochemical stain to be done on the first and second stage of tissue excision. You bill 17311 and 17312x2 for the Mohs surgery plus 88314-59x3 for the frozen section special stains.

Answer: Correct. One bills one unit of service for each special stain and for each block stained. As one special stain was used, and there were two tissue blocks in the first stage and one in the third stage, three units of special staining were done.

Example 2: You excise a lentigo maligna melanoma on the face with two stages of Mohs surgery. Each stage was processed into three blocks of tissue. Slides from each block from both stages were separately stained with melan-A and HMB-45 immunoperoxidase stains. You then bill for the immunoperoxidase staining as 88342-59x6 for one stain and 88343-59x6 for the second stain.

Answer: Incorrect. The two stains were applied to separate slides. Consequently, 88343 is not appropriate, as it codes for more than one immunohistochemical stain applied to one and the same slide. As CPT 88342 codes for each individual antibody used per block, one would code 88342 with 6 units (tissue from a total of six blocks) for the melan-A stain and 88342 with an additional 6 units for the HMB-45 stain, for a total of 12 units of staining. The appropriate coding would be: 88342-59x12. [pagebreak]

Example 3: You have a histology processing laboratory on your office premises. Your laboratory performs both the technical slide preparation component and the slide interpretation. You excise a broad skin lesion on a leg, process the formalin-fixed tissue into two portions on two separate blocks, and discover that it is an extensive granulomatous dermatitis. You then obtain PAS and Fite stains on sections from both blocks. You bill CPT 88305 for the one tissue specimen interpretation plus CPT 88313-59x4 for the two special stains.

Answer: Correct. Two special stains were done, and each of the two special stains was done on slide specimens from two tissue blocks. This generated a total of four billable units of service. The 59 modifier is used to distinguish the service provided separate from the 88305 global pathology code, and the x4 multiplier signifies the four units of service provided.

11306, not 17306

A single-digit error can be a big problem in coding — or a coding column. In our January Cracking the Code, we used code 17306 when we meant 11306. The corrected example appears below. The full article, with the correction, is available at

Example 2: You shave off a 0.5 cm wide lesion suspicious for a basal cell carcinoma on the neck. The maximum diameter of the shave is 0.8 cm. You await the histopathologic diagnosis prior to submitting your bill. The histopathology confirms the presence of a basal cell carcinoma with cut tissue edges free of tumor. As you apparently fully treated the tumor, you bill CPT 17271, malignant destruction on the neck (lesion diameter 0.6 to 1.0 cm).

Answer: Incorrect. Although the lesion was fully removed, the procedure done does not fit the destruction code definition. The CPT Assistant, August 2009 issue, p. 7, specifies that destruction is “not removal by excision or shaving of skin lesions using surgical instruments such as a knife, scalpel, or other similar tools.” Consequently, the appropriate CPT code is either biopsy, 11100, or shaving of epidermal or dermal lesion, 11306.



11306, not 17306