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ICD-10 Guide
ICD-10 CodesB27.91

B27.91

Infectious mononucleosis, unspecified with polyneuropathy

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/05/2025

Code Description

ICD-10 B27.91 is a billable code used to indicate a diagnosis of infectious mononucleosis, unspecified with polyneuropathy.

Key Diagnostic Point:

Infectious mononucleosis, commonly caused by the Epstein-Barr virus (EBV), is characterized by fever, sore throat, lymphadenopathy, and fatigue. In some cases, patients may develop polyneuropathy, which is a condition that affects multiple peripheral nerves, leading to symptoms such as weakness, numbness, and pain. The pathophysiology of infectious mononucleosis involves the proliferation of B-lymphocytes and the immune response to the EBV infection. Diagnosis typically involves clinical evaluation and laboratory tests, including heterophile antibody tests (e.g., Monospot test) and specific EBV serologies. While most cases resolve spontaneously, antiviral treatments such as acyclovir may be considered in severe cases or when complications arise. The presence of polyneuropathy complicates the clinical picture, as it may require additional diagnostic workup and management strategies, including physical therapy and pain management.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between infectious mononucleosis and other viral infections.
  • Identifying the presence of polyneuropathy and its etiology.
  • Need for comprehensive documentation of symptoms and laboratory findings.
  • Potential for overlapping symptoms with other conditions.

Audit Risk Factors

  • Inadequate documentation of polyneuropathy symptoms.
  • Failure to provide laboratory results supporting the diagnosis.
  • Misclassification of the type of infectious mononucleosis.
  • Lack of clarity in the relationship between mononucleosis and polyneuropathy.

Specialty Focus

Medical Specialties

Infectious Disease

Documentation Requirements

Detailed history of symptoms, laboratory test results, and treatment plans.

Common Clinical Scenarios

Patients presenting with classic symptoms of mononucleosis and neurological complaints.

Billing Considerations

Consideration of differential diagnoses and potential complications.

Neurology

Documentation Requirements

Neurological examination findings, diagnostic imaging results, and treatment protocols.

Common Clinical Scenarios

Patients with neurological symptoms following a recent viral infection.

Billing Considerations

Assessment of nerve conduction studies and potential need for multidisciplinary management.

Coding Guidelines

Inclusion Criteria

Use B27.91 When
  • Follow official ICD
  • 10 coding guidelines, ensuring accurate documentation of both infectious mononucleosis and polyneuropathy
  • Include relevant laboratory findings and clinical assessments to support the diagnosis

Exclusion Criteria

Do NOT use B27.91 When
No specific exclusions found.

Related CPT Codes

86790CPT Code

EBV antibody test

Clinical Scenario

Used to confirm EBV infection in suspected cases of mononucleosis.

Documentation Requirements

Document the reason for testing and results.

Specialty Considerations

Infectious disease specialists may require additional serological tests.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of conditions like infectious mononucleosis with complications, improving data accuracy and patient care tracking.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of conditions like infectious mononucleosis with complications, improving data accuracy and patient care tracking.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of conditions like infectious mononucleosis with complications, improving data accuracy and patient care tracking.

Resources

Clinical References

  • •
    CDC - Infectious Mononucleosis

Coding & Billing References

  • •
    CDC - Infectious Mononucleosis

Frequently Asked Questions

What are the common symptoms of infectious mononucleosis?

Common symptoms include fever, sore throat, swollen lymph nodes, and fatigue. Some patients may also experience headaches, rash, and splenomegaly.

How is polyneuropathy diagnosed in the context of infectious mononucleosis?

Diagnosis of polyneuropathy involves clinical evaluation, neurological examination, and may include nerve conduction studies to assess nerve function.