Chapter 18: CPT® Section Pathology & Laboratory Workbook Answers and Rationale.

Case 1
R/O MRSA—Central line catheter
Clinical Indications: |1| Patient with fever not responsive to antibiotics

Collected: 03/30/XX 17:45 Accession Num: TXXXXX Status: Authenticated

Method: Single nucleic acid sequence |2|
Culture: Methicillin resistant Staphylococcus aureus (MRSA) isolated |3|

|1| Clinical indications provide medical necessity when there are no other findings.
|2| Note the method used to identify the infectious agent and/or resistance.
|3| Select the diagnosis code based on the findings.

What are the CPT® and ICD-10-CM codes reported?
CPT® code: 87641
ICD-10-CM code: A49.02

Rationale:
CPT® code: The test is performed to detect if the patient has MRSA. The method used is nucleic acid sequence. In the CPT®
Index, look for Infectious Agent/Antigen Detection/Nucleic acid Probe/Staphylococcus Aureus referring you to 87640-87641.
The findings confirm it is Methicillin resistant report 87641.

ICD-10-CM code: The diagnosis is MRSA. In the ICD-10-CM Alphabetic Index, look for MRSA (Methicillin resistant
staphylococcus aureus)/infection or Infection/methicillin/resistant staphylococcus aureus (MRSA) referring you to A49.02.
Verify code selection in the Tabular List.

Case 2
Requesting Provider: CI, MD

Surgical Pathology Report: Collected: Received: 3/4/20XX, the pathologist providing the service is an employee of the lab.

Materials Received for Consultation: Three referred specimens described as left base of tongue, left tonsil and right tonsil |1|

Clinical Data: Slides are prepared and reviewed in conjunction with the patient being seen for Radiation Oncology consultation for
carcinoma of base of tongue |2|

Final Diagnosis:
Eight slides prepared and reviewed A-H. |3|

Left base of tongue (part A) and right tonsil, biopsies (parts B, C, G): Squamous mucosa and tonsillar tissue; no carcinoma
identified. |3|


Left tonsil, biopsies (parts D, E, F, H): Tonsillar tissue with no carcinoma identified. |3|

|1| There are three specimens.
|2| Use this diagnosis as consultation on referred materials is negative.
|3| A total of eight slides are prepared and reviewed.

What are the CPT® and ICD-10-CM codes reported?
CPT® code: 88323
ICD-10-CM code: C01

Rationale:
CPT® code: A consultation and slide preparation is performed. In the CPT® Index, look for Consultation/Surgical Pathology.
This is reported with 88323. Consultation and report on referred material requiring preparation of slides is reported per
surgical case, not by the number of specimens. Only one unit is reported.

ICD-10-CM code: Cancer is not found in the tonsillar tissue but the patient is diagnosed with cancer in the base of the tongue.
In the ICD-10-CM Alphabetic Index, look for Cancer – see also Neoplasm, by site, malignant. In the Table of Neoplasms, look
for Neoplasm, neoplastic/tongue/base (dorsal surface)/Malignant Primary column referring you to C01. Verify code selection
in the Tabular List. There is an instructional note to use an additional code for alcohol abuse/dependency or tobacco abuse/
dependency. The case note does not give that information so it will not be coded.

Case 3
Requested by P Norris, MD

Surgical Pathology Report
Materials Received: Referred slides of inguinal lymph node |1|
Clinical Data: History of Merkel cell carcinoma.
Final Diagnosis: Lymph node, left inguinal, excision:
1. High grade neuroendocrine carcinoma |2| involving one of four lymph nodes (1/4); see Comment.
2. No extranodal extension identified.

Comment: The neoplasm consists of sheets of small round blue cells with powdery chromatin, scant cytoplasm, and indistinct cell
borders. Numerous mitotic figures and areas of single cell necrosis are seen. The morphologic findings are consistent with a high
grade neuroendocrine carcinoma and the differential diagnoses include metastatic Merkel cell carcinoma or small cell carcinoma.
|3|
Given the patient’s reported history (slides not reviewed at UMMM), the features are consistent with metastatic Merkel cell
carcinoma. Correlation with clinical findings is advised.

|1| Consultation on referred slides.
|2| This is the only definitive diagnosis reported.
|3| Even though these diagnoses are given in the differential diagnoses, the final diagnosis indicates a specific malignant
carcinoma, so this is coded.

What are the CPT® and ICD-10-CM codes?
CPT® code: 88321
ICD-10-CM code: C7A.1

Rationale:
CPT® Code: In the CPT® Index, look for Pathology and Laboratory/Surgical Pathology/Consultation referring you to 88321-
88325. A consultation with review of slides prepared elsewhere is reported with 88321. Only one specimen is reviewed so the
code is only reported once.

ICD-10-CM code: The differential diagnoses are not reported until they are confirmed. The only definitive diagnosis
documented is metastatic high grade neuroendocrine carcinoma. In the ICD-10-CM Alphabetic Index, look for Carcinoma/
neuroendocrine/high grade, any site referring you to C7A.1. Note, neuroendocrine carcinoma is listed under final diagnosis.
Verify code selection in the Tabular List.

Case 4
Surgical Pathology
Ordering Physician:
Karen Smith, MD

Procedures: Surgical pathology procedure performed by a pathologist.

Clinical Indications: Patient presents to her gynecologist for follow-up of an abnormal Papanicolaou (Pap) smear.|1| The physician
refers patient for repeat Pap smear. The specimen is sent for interpretation and report by the pathologist providing consultative
services.

Specimens: Pap smear, cervix.

Methodology: Morphometric analysis Fluorescent In Situ Hybridization (FISH) using computer-assisted technology, professional
component.|2|


Results: The pathologist reviews images from the slides. The pathologist does not identify any copies of the 3q26 |3| and 5p15 |4|
genes in the stained slide images. This report is consistent with the patient’s HPV results and the patient is not at presently at risk to
develop severe dysplasia.

A 41-year-old female presents to her gynecologist to review her abnormal Pap results. The physician reviews her Pap results which
indicates that this patient is at risk for cervical cancer. The gynecologist recommends the patient have a repeat Pap smear and FISH
studies to evaluate the tissue for the 3q26 and 5p15 genes which are associated with increased risk to develop cervical dysplasia.

FISH studies may be ordered by gynecologist to evaluate the presence of copies of the 3q26 and 5p15 genes. The presence of these
genes is associated with an increased risk to develop severe cervical dysplasia, and place the patient at a higher risk to develop
invasive cervical cancer.

The patient decides to have these studies and the physician performs a Pap smear on the same day. The specimen is sent for both
HPV testing and probe studies for the 3q26 and 5p15 genes.

Pathologist does the review and the interpretation and report of the FISH probes and reports that from the Pap smear probes 3q26
and 5p15 are not present in this patient’s cervical Pap smear specimen.

Referring physician sends the patient’s results of the FISH studies which include the pathologist’s interpretation and report.

|1| Diagnosis used for lab
|2| Procedure performed
|3| Initial stain
|4| Additional stain

What are the CPT® and ICD-10-CM codes reported?
CPT® codes: 88367, 88373
ICD-10-CM code: R87.619

Rationale:
CPT® code: Look in the CPT® Index for Fluorescent In Situ Hybridization (FISH)/Probe/Morphometric Analysis Computer-
Assisted referring you to 88367, 88373, and 88374. These codes are located in the Surgical Pathology code section. You will
look in this subsection where you will find the morphometric analysis code 88367 to report the initial single stain procedure
for probe 3q26 and add-on code 88373 to report additional single stain probe, 5p15.

ICD-10-CM code: Look in the ICD-10-CM Alphabetic Index for Abnormal, abnormality, abnormalities/Papanicolaou (smear)/
cervix referring you to R87.619. Verify code selection in the Tabular List

Case 5
Clinical Indications: The patient is a 28-year-old female for routine lab tests part of her yearly physical exam.
Collected: 04/14/XX 13:29 Patient number: xxxxxxxxxxx ID: verified
Site: right antecubital venipuncture Disposition: outpatient, fasting
Tests: metabolic |1| & CBC |2|

Results:
Sodium Blood: 141 mEq/L (135-145)
Potassium Blood: 4.0 mEq/L (3.3-4.8)
Chloride Blood: 105 mEq/L (95-105)
Carbon Dioxide Blood: 24 mmol/L (23-30)
Urea Nitrogen Blood: 12 mg/dL (5-25)
Creatinine Blood: 0.86 mg/dL (0.70-1.50)
Glucose Blood: 93 mg/dL (70-110)
Calcium Blood (total): 9.3 mg/dL (8.5-10.5) |3|
CBC: (automated) |4|
WBC: 6.9 thou/uL (3.9-10.3) Hemoglobin Blood: 14.5 g/dL (11.8-16.0)
Platelet Count: 235 thou/uL (135-370) Red Blood Cells: 5.02 mil/uL (4.00-5.50)

Impression: Normal labs HCT: 40% (38-46%)

|1| Metabolic Panel is a set of tests performed as a panel in CPT®. Review the two metabolic panels to see if one includes the tests
performed.
|2| CBC is not included in either metabolic panels and is reported separately.
|3| The calcium is total instead of ionized.
|4| CBC is automated with no differential.

What are the CPT® and ICD-10-CM codes for the pathologist?
CPT® codes: 80048, 85027
ICD-10-CM code: Z00.00

Rationale:
CPT® codes: All elements of a basic metabolic panel (80048) are performed. In the CPT® Index, look for Blood Tests/Panels/
Metabolic/Basic. The calcium is indicated as total, not listed as ionized.

The CBC is Complete Blood Count. In the CPT® Index, look for Complete Blood Count (CBC)—See Blood Cell Count; Blood Cell
Count/Complete (CBC) referring you to codes 85025-85027. Because there is not WBC differential, 85027 is the correct code.

ICD-10-CM code: The blood work performed is for routine lab tests. In the ICD-10-CM Alphabetic Index, look for Examination/
laboratory (as part of a routine general medical examination Z00.00. Verify code selection in the Tabular List.

The results of the lab tests are normal.

Case 6
Requested by R Simon, MD
Cytology |1| Report: Collected: 1/26/20XX Received: 1/27/20XX, Pathologist performing the service is an employee of the lab.
Specimen Source: A. Peritoneal Fluid
Specimen Description: 100 mls yellow fluid
Cytopreparation: 2 ccf

Pertinent Clinical Data and Clinical Diagnosis: 26-year-old female with end-stage renal disease (ESRD) due to type 1 diabetes
presents for elective kidney transplant. |2|


Cytologic Impression: Peritoneal dialysis drain fluid: No cytologically malignant cells are identified.

Comment: 100 mls yellow fluid is received from which two Papanicolaou stained cytocentrifuged |3| slides are made. Slides contain
mesothelial cells with a spectrum of reactive changes and histiocytes. No malignant cells are identified. |4|

|1| Report indicates type of procedure performed.
|2| Use clinical diagnostic information to assign ICD-10-CM codes because the findings are negative.
|3| A concentration technique is used on the smear.
|4| Findings are negative.

What are the CPT® and ICD-10-CM codes?
CPT® code: 88108
ICD-10-CM codes: E10.22, N18.6, Z99.2

Rationale:
CPT® code: The test performed is cytopathology on the peritoneal fluid. The documentation indicates cytocentrifuged,
meaning that the fluid was removed to concentrate the cells for the smears placed on the slides. In the CPT® Index, look for
Cytopathology/Smears/Concentration Technique referring you to 88108. Review of the code description verifies 88108 is the
correct code.

ICD-10-CM codes: The patient is diagnosed with type 1 diabetes and end-stage renal disease (ESRD). The patient presents
for a kidney transplant but the procedure has not been performed yet. The ESRD is a manifestation of the diabetes. In the
ICD-10-CM Alphabetic Index, look for Diabetes/type 1/with/chronic kidney disease referring you E10.22. In the Tabular List
there is an instructional note for E10.22 to use additional code to identify stage of chronic kidney disease (N18.1-N18.6).
The patient has end-stage renal disease (ESRD) N18.6. There is an instructional note for N18.6 to use additional code to
identify dialysis status (Z99.2). Because the case note under Cytologic impression states, “Peritoneal dialysis drain fluid” it is
appropriate to also report Z99.2.

Case 7
Requested by D Smith, MD. The pathologist providing the service is an employee of the lab.

Surgical Pathology Report
Clinical Data: Chronic infected skin ulcer status post amputation of first and third toes, current mid transmetatarsal amputation.

Gross and Microscopic Description: A) Received in formalin designated “right mid transmetatarsal amputation” |1| is a distal right
foot including second, fourth, and fifth toes, measuring 9.0 x 9.0 x 4.0 cm. Also in the container is a piece of tan bone measuring
2.4 x 1.3 x 1.3 cm. |2|
The skin and subcutaneous tissue recedes up to 4.0 cm from the smooth bony margins of resection. The skin
is tan-white. The first and third toes are missing. The remaining toes are slightly flexed and with a thickened irregular nail of the
second toe. There is a round, deep ulcer at the bottom of the foot |3| proximal to the second toe, measuring 1.5 x 1.5 x 0.7 cm. No
other lesions are identified. The piece of bone is submitted for decalcification. |4| Representative sections are submitted in A1 and
A2, including skin and soft tissue margins.

Final Diagnosis: A) Right foot, mid-transmetatarsal amputation:
1. Right foot with ulceration
2. Status post amputation of first and third toes.
3. Skin and soft tissue margins histologically viable. |5|
4. Bone section pending decalcification, addendum report to follow. |6|

Comment: Geographic fibrinoid necrosis associated with ulcer raises the possibility of a rheumatoid nodule.
Microscopic Description: Microscopic examination was performed.
Findings of decalcified |7| specimen (A3).
Sections of the bone demonstrate chronic reactive changes. No evidence of active osteomyelitis is identified.

|1| The specimen that is received.
|2| Bone specimen is also sent for testing.
|3| Diagnosis to report and specificity of where the ulcer is located.
|4| Decalcification is reported separately.
|5| Although there are no specific listings for amputations, the skin margins had to be examined for viability.
|6| The bone fragments were examined for pathologic components and should be treated similar to pathologic fracture fragments.
|7| Special treatment by decalcification is coded separately.

What are the CPT® and ICD-10-CM codes?
CPT® codes: 88307, 88311
ICD-10-CM codes: L97.511

Rationale:
CPT® codes: The operative note indicates Gross and Microscopic description (exam) performed on the specimens. In the
CPT® Index, look for Pathology and Laboratory/Surgical Pathology/Gross and Micro Exam. Levels II through VI are reported
with 88302-88309. To determine which level to report, review the description for each code. 88307 is reported for extremity,
amputation, non-traumatic; this is because the amputation was of the mid transmetatarsal (mid foot). Decalcification is
a procedure where mineral or other calcified tissue so section can be cut histologic (microscopic) exam. Decalcification is
reported separately. In the CPT® Index, look for Pathology and Laboratory/Surgical Pathology/Decalcification Procedure
referring you to 88311.

ICD-10-CM codes: The patient is diagnosed with an ulcer of the right foot. In the ICD-10-CM Alphabetic Index, look for Ulcer/
foot – see Ulcer, lower limb. Look for Ulcer/lower limb/foot specified NEC/right/with skin breakdown only referring you
L97.511. Verify code selection in the Tabular List.

Case 8
Requested by R Williams, MD

Surgical Pathology Report Collected: 2/1/20XX Received: 2/2/20XX. The pathologist is employed by the lab providing the service.

Clinical Data: 26-year-old with end-stage renal (ESRD) disease due to type 1 diabetes, status post kidney, pancreas transplant with
subsequent pancreas allograft removal, now with disseminated intravascular coagulation and decreased urine output and kidney
allograft showing no flow to the kidney.

Description:
A) Received fresh designated “ureteral stent-gross only” |1| is a 15 cm x 0.2 cm piece of plastic tubing with a 1.5 cm hairpin turn
at either end. There are 0.05 cm holes at every 2 cm of the device.
B) Received fresh in a container labeled “removed kidney-gross and micro” |2| is a 138 gram, 11 x 7 x 3 cm kidney. The specimen
has a smooth, glistening, pink capsule with lightly adherent fibrous tissue. There are multiple surgical clips within the hilum
and perihilar fat. The specimen is bivalved to reveal a sharp but irregular demarcation at the cortex and the medullary
interface. No masses, nodules or lesions are grossly appreciated. There is probable intravascular thrombus. Representative
sections are submitted as follows: B1—renal vein, renal artery and ureteral margins; B2-B5—representative sections of
kidney parenchyma in relation to capsule. |3|

Final Diagnosis:
A) Medical device, removal: Pigtail catheter (gross only).
B) Kidney, allograft resection:
1. Widespread acute coagulative necrosis/infarct of renal parenchyma in the setting of multifocal microvascular thrombi
(clinical history of disseminated intravascular coagulation). |4|
2. Focal renal arterial thrombosis. |4|
3. No evidence of humoral or cellular rejection.

|1| Specimen 1.
|2| Specimen 2.
|3| Although the specimen is split into several sections, it only represents one specimen so can only be billed once.
|4| Use this data to assign a diagnosis code.

What are the CPT® and ICD-10-CM codes?
CPT® codes: 88307, 88300
ICD-10-CM codes: T86.19, N28.0

Rationale:
CPT® codes: There are two specimens examined, the ureteral stent and the kidney. The ureteral stent was only examined
grossly. In the CPT® Index, look for Pathology and Laboratory/Surgical Pathology/Gross Exam/Level I. This procedure is
reported with 88300.

The kidney was examined both grossly and microscopically. In the CPT® Index, look for Pathology and Laboratory/Surgical
Pathology/Gross and Micro Exam/Level V. The gross and microscopic exam of the kidney is reported with 88307.

ICD-10-CM codes: The patient is status post kidney transplant with a complication (thrombosis of the renal artery). In the
ICD-10-CM Alphabetic Index, look for Complication(s) (from) (of)/transplant/kidney/specified type NEC referring you to
T86.19. An additional code is selected to report the renal artery thrombosis. In the Alphabetic Index, look for Thrombosis/
renal (artery) referring you to N28.0. Verify code selection in the Tabular List.

Case 9
Requested by D Freeman, MD

Surgical Pathology Report: Collected: 4/20/20XX Received: 4/20/20XX. The pathologist providing the service is an employee of the
lab.

Clinical Data: Post-heart transplant, rule out rejection.

Gross Description: |1|
A) Received in a scant amount of formalin labeled “right ventricle endomyocardium” |2| are seven tan-brown, irregular soft
tissues averaging 0.1 cm in greatest dimension. The specimen is submitted in toto in cassette A1.
B) Received in a vial of immunofluorescence fixative labeled “right ventricle endomyocardium” |3| are two tan, irregular soft
tissues averaging 0.1 cm in greatest dimension. Specimen is entirely submitted for immunofluorescence.

Microscopic Description:
A) Sections of the paraffin-embedded material show six fragments of myocardium which are adequate to evaluate. There
are few mononuclear cells present within the tissue, but these are beneath the threshold required to diagnose biologically
meaningful rejection.
No cell injury is seen and no inclusion bodies are noted.

B) Sections of the frozen myocardium demonstrate two fragments of myocardium and one fresh blood clot. There is no
inflammatory cell infiltrate.

Immunofluorescence Report: Tissue, received in transport media, is washed in buffer and snap frozen in liquid nitrogencooled
isopentane. Acetone-fixed frozen sections of the snap-frozen tissue are incubated with fluorescein-conjugated polyclonal
antibodies to IgG, IgM, IgA, C3, C1q, fibrinogen, and albumin. Localization is thus via direct immunofluorescence. |4| Indirect
immunofluorescence staining of peritubular capillaries for C4d. |5|


Block (Original Label): B Population: Microvascular endothelium

Label Marker For Results ❘ Special Pattern or Comments ❘
❘C4d ❘ C4d (Quidel Clone A213), ❘ 2+ ❘ Venule staining with high interstitial
immunofluorescence ❘ background

Block (Original Label): B1 Population: Microvascular endothelium

Label Marker For Results ❘ Special Pattern or Comments ❘
IgG IF ❘ IgG, immunofluorescence ❘ Negative Interstitial staining
IgA IF ❘ IgA, immunofluorescence ❘ Negative
❘ IgM IF ❘ IgM, immunofluorescence ❘ 2+ Capillary and venule staining
❘ C3 IF ❘ C3, immunofluorescence ❘ 2+ Venule staining
❘ C1q IF ❘ C1q, immunofluorescence ❘ 2+ Venule staining
FIB IF ❘ Fibrinogen, immunofluorescence ❘ Negative ❘ Diffuse interstitial staining
ALB IF ❘ Albumin, immunofluorescence ❘ Negative ❘ Diffuse interstitial staining

Final Diagnosis: A, B) Right ventricular endomyocardial biopsy:
1. No significant cellular rejection.
2. Immunofluorescence studies positive for humoral/vascular rejection (IgM and complement present). Please see comment.

Comment: A, B) This is the fourth biopsy since transplant. Compared to his most recent biopsy, the current specimen shows no
change in the degree of cellular rejection.

|1| Two specimens are received, one for gross and microscopic and one for immunofluorescence.
|2| Specimen 1
|3| Specimen 2
|4| Indicates direct immunofluorescence.
|5| Note that indirect immunfluorescence is coded separately.

What are the CPT® and ICD-10-CM codes?
CPT® codes: 88307 x 2, 88346, 88350 x 7
ICD-10-CM code: T86.21

Rationale:
CPT® Codes: Two tissue specimens from the endomyocardium were separately identified and are sent for a gross and
microscopic exam as well as a separate specimen for immunofluorescence. In the CPT® Index, look for Pathology and
Laboratory/Surgical Pathology/Gross and Micro Exam. This lists the possible levels, Level II-VI. It is necessary to look at the
lists with these different codes. Code 88307, Level V, lists “Myocardium, biopsy.” The gross and microscopic exam for this
tissue is reported with 88307 x 2. In the CPT® Index, look for Immunofluorescence Microscopy/Antibody Stain Procedure
referring you to 88346 and 88350. In this case, 8 antibodies are tested, so it is reported as 88346 for the initial stain, and
88350 x 7 for each additional stain. Notice, in the add-on code descriptor it says: each additional single antibody stain.

ICD-10-CM code: The patient is diagnosed with rejection of the heart transplant. In the ICD-10-CM Alphabetic Index, look for
Rejection/transplant/heart referring you T86.21. Verify code selection in the Tabular List

Case 10
Clinical Indications: Inpatient day 32 in ICU with fever, hematuria, generalized edema, pneumonia |1|
Urine |2| Fungal Culture: Urine

Special Requests: None
Culture: No fungus isolated in 30 days |3|
Lower Resp Fungal W/Dir. Exam: Sputum |4|

Special Requests: None
Stain for Fungus: No fungi seen |5|
Culture: One colony Candida albicans |6|

Blood Fungal Culture: |7| Blood Arm, Right
Special Requests: Aerobic bottle
Culture: No fungus isolated in 4 weeks

Blood Fungal Culture: Blood Right IJ Catheter SWAN |8|
Special Requests: Aerobic bottle
Culture: No fungus isolated in 4 weeks

|1| Used for diagnoses coding.
|2| Note the substance the specimen was collected from.
|3| Since no fungus has been found in the analyte, the clinical indication must be used. Link this service to the hematuria
diagnosis.
|4| This specimen is from sputum. The information is needed to select the correct code.
|5| Since no fungi have been identified assign the pneumonia code for this service.
|6| This result is too limited to assign a diagnosis code.
|7| Again, the source material is required to code the service and the clinical indications are used for the diagnosis since there are
no findings.
|8| The analysis using blood can be billed twice since there are two different source locations.

What are the CPT® and ICD-10-CM codes?
CPT® codes: 87102, 87102-59, 87103, 87103-59
ICD-10-CM codes: J18.9, R31.9, R60.1

Rationale:
CPT® codes: There are several specimens obtained (urine, sputum and blood) to perform cultures. In the CPT® Index, look
for Culture/Fungus/Source Other than Blood for the sputum and urine. Code 87102 is reported twice (urine, sputum). Next,
locate the code for the blood specimen. In the CPT® Index, look for Culture/Fungus/Blood. Code 87103 is reported twice
because blood samples are taken from two different sites. According to CPT® subsection guidelines for Microbiology, for
multiple specimens/sites use modifier 59. When the same test is performed on different specimen(s) that uses the same CPT®
code modifier 59 is appropriate to use.

ICD-10-CM codes: The patient is stated as having fever, hematuria, generalized edema and pneumonia. Pneumonia indexes
to J18.9 in the ICD-10-CM Alphabetic Index and is listed first. Fever (R50.9) is a symptom of the pneumonia and is not
reported separately. Look in the Alphabetic Index for Hematuria referring you to R31.9 and Edema/generalized referring you
to R60.1. Verify code selection in the Tabular List.