Definition of Lymphadenopathy
Lymphadenopathy refers to abnormalities in the size, consistency, or morphological characteristics of lymph nodes. 1, 2, 3
Core Defining Features
Size criteria:
- Lymph nodes larger than 1 cm in short-axis diameter are generally considered enlarged 4
- Epitrochlear nodes greater than 5 mm in diameter are abnormal 5
- Palpable supraclavicular, popliteal, and iliac nodes are inherently abnormal regardless of size 5
Consistency and morphology:
- Lymph nodes that are hard, matted, or fused to surrounding structures suggest malignancy or granulomatous disease 1
- Changes in consistency (firm vs. soft) and mobility are key distinguishing features 2, 3
Clinical Classification
Duration-based definition:
- Any lymphadenopathy persisting beyond 2 weeks warrants investigation 3
- Lymphadenopathy lasting more than 4 weeks requires imaging and laboratory evaluation 1
- Chronic lymphadenopathy in autoimmune lymphoproliferative syndrome (ALPS) is defined as persistent for ≥6 months 6
Distribution patterns:
- Localized lymphadenopathy: Abnormal nodes in a single anatomic region, typically reflecting regional infection or malignancy 1, 5
- Generalized lymphadenopathy: Involvement of two or more non-contiguous nodal regions, usually indicating systemic disease 1, 5
Epidemiologic Context
Lymphadenopathy occurs in 0.6% of the population annually, with the majority of cases being benign 1. However, specific anatomic locations and patient characteristics significantly alter the probability of serious underlying disease, making the definition clinically meaningful only when combined with these contextual factors 5.
Common pitfall: The term "lymphadenopathy" is purely descriptive and does not imply a specific diagnosis—it encompasses everything from self-limited viral infections to life-threatening malignancies 2, 7. Therefore, identifying lymphadenopathy is merely the starting point for systematic evaluation rather than a diagnosis itself.