Cytopathologic Diagnosis of Non-Neoplastic Inflammatory Disorders of Lymphoid Organs

Fine-needle aspiration biopsy (FNAB) is a minimally invasive, cost-effective, and accurate method for evaluating enlarged lymph nodes, especially useful in pediatric cases where most aspirates are benign. It can be performed by palpation or under ultrasound guidance for deeper lesions. Rapid onsite evaluation enhances specimen adequacy and guides ancillary testing. FNAB, often combined with flow cytometry, can reduce the need for surgical biopsies by up to 86%, with reported sensitivity and specificity of 85-95% and 98-100%, respectively.

Despite its advantages, FNAB is sometimes undervalued due to misconceptions about its diagnostic capabilities. The recently introduced WHO Reporting System for Lymph Node, Spleen, and Thymus Cytopathology, based on the Sydney System, aims to standardize reporting. It categorizes aspirates into five diagnostic groups, each with an associated risk of malignancy (ROM) and management recommendations. The "benign" category is the most common and includes non-neoplastic inflammatory conditions. Cytopathologists assess cellularity and cytologic features to distinguish benign from atypical or malignant processes. Low-power evaluation of smear patterns helps differentiate infectious from reactive causes. Flow cytometry is crucial for identifying lymphoproliferative disorders and leukemic infiltrates. The ROM for benign FNABs ranges from 2 to 16%, with a pooled estimate of 5%. Management typically involves clinical follow-up, with repeat FNAB or biopsy reserved for persistent or suspicious cases. Familiarity with lymph node cytology and integrated diagnostic approaches is essential for accurate patient care.

Familiarity with lymph node cytology and integrated diagnostic approaches is essential for accurate patient care.