ICD-10: C82.39

Follicular lymphoma, particularly grade IIIa, is a subtype of non-Hodgkin lymphoma characterized by specific histological features and clinical presentations. The ICD-10 code C82.39 specifically refers to follicular lymphoma grade IIIa that occurs in extranodal and solid organ sites. Understanding the diagnostic criteria for this condition is essential for accurate coding and treatment planning.

Diagnostic Criteria for Follicular Lymphoma Grade IIIa

1. Histological Examination

• Tissue Biopsy: A definitive diagnosis of follicular lymphoma grade IIIa typically requires a biopsy of the affected tissue. This can be obtained from lymph nodes or extranodal sites.
• Histopathology: The biopsy is examined microscopically to identify the characteristic follicular architecture. In grade IIIa, there is a predominance of large cells (centroblasts) within the follicles, with a higher number of these cells compared to lower grades of follicular lymphoma.

2. Immunophenotyping

• Immunohistochemistry: The use of specific antibodies to identify cell surface markers is crucial. Follicular lymphoma cells typically express CD10, CD19, CD20, and BCL2. The presence of BCL6 can also be indicative of follicular lymphoma.
• Flow Cytometry: This technique may be used to analyze the surface markers on the lymphoma cells, confirming their B-cell lineage and the presence of the characteristic markers.

3. Cytogenetic Analysis

• Chromosomal Abnormalities: The presence of the t(14;18) translocation, which results in the overexpression of the BCL2 gene, is a hallmark of follicular lymphoma. This genetic alteration can be detected through techniques such as fluorescence in situ hybridization (FISH).

4. Clinical Presentation

• Symptoms: Patients may present with lymphadenopathy, splenomegaly, or symptoms related to extranodal involvement, such as abdominal pain or organ dysfunction.
• Staging: The Ann Arbor staging system is often used to determine the extent of the disease, which is crucial for treatment planning. Extranodal involvement is classified as stage IV.

5. Exclusion of Other Conditions

• Differential Diagnosis: It is important to rule out other types of lymphomas and hematological malignancies that may present similarly. This may involve additional imaging studies and laboratory tests.

Conclusion

The diagnosis of follicular lymphoma grade IIIa, particularly in extranodal and solid organ sites, relies on a combination of histological, immunophenotypic, and cytogenetic evaluations, alongside clinical assessments. Accurate diagnosis is essential for appropriate treatment strategies and coding under ICD-10 C82.39. Clinicians must ensure that all diagnostic criteria are met to provide the best care for patients with this complex condition.