Diagnosis

Is the mass a lymph node? Nonlymphoid masses (cervical rib, thyroglossal cyst, branchial cleft cyst or infected sinus, cystic hygroma, goiter, sternomastoid muscle tumor, thyroiditis, thyroid abscess, neurofibroma) occur frequently in the neck and less often in other areas. Is the node enlarged? Lymph nodes are not usually palpable in the newborn. With antigenic exposure, lymphoid tissue increases in volume. They are not considered enlarged until their diameter exceeds 1 cm for cervical and axillary nodes and 1.5 cm for inguinal nodes. Other lymph nodes usually are not palpable or visualized with plain radiographs. What are the characteristics of the node? Acutely infected nodes are usually tender. There may also be erythema and warmth of the overlying skin. Fluctuance suggests abscess formation. Tuberculous nodes may be matted. With chronic infection, many of these signs are not present. Tumor-bearing nodes are usually firm and nontender and may be matted or fixed to the skin or underlying structures.

Is the lymphadenopathy localized or generalized? Generalized adenopathy (enlargement of >2 noncontiguous node regions) is caused by systemic disease (Table 484-1) and is often accompanied by abnormal physical findings in other systems. In contrast, regional adenopathy is most frequently the result of infection in the involved node and/or its drainage area (Table 484-2). When due to infectious agents other than bacteria, adenopathy may be characterized by atypical anatomic areas, a prolonged course, a draining sinus, lack of prior pyogenic infection, and unusual clues in the history (cat scratches, tuberculosis exposure, venereal disease). A firm, fixed node should always raise the question of malignancy, regardless of the presence or absence of systemic symptoms or other abnormal physical findings.

Table 484-1 DIFFERENTIAL DIAGNOSIS OF SYSTEMIC GENERALIZED LYMPHADENOPATHY

INFANT	CHILD	ADOLESCENT
COMMON CAUSES
Syphilis	Viral infection	Viral infection
Toxoplasmosis	EBV	EBV
CMV	CMV	CMV
HIV	HIV	HIV
	Toxoplasmosis	Toxoplasmosis
	Toxoplasmosis	Syphilis
RARE CAUSES
Chagas disease (congenital)	Serum sickness	Serum sickness
Congenital leukemia	SLE, JRA	SLE, JRA
Congenital tuberculosis	Leukemia/lymphoma	Leukemia/lymphoma/Hodgkin disease
Reticuloendotheliosis	Tuberculosis	Lymphoproliferative disease
Lymphoproliferative disease	Measles	Tuberculosis
Metabolic storage disease	Sarcoidosis	Histoplasmosis
Histiocytic disorders	Fungal infection	Sarcoidosis
	Plague	Fungal infection
	Langerhans cell histiocytosis	Plague
	Chronic granulomatous disease	Drug reaction
	Sinus histiocytosis	Castleman disease
	Drug reaction	Castleman disease

CMV, cytomegalovirus; EBV, Epstein-Barr virus; HIV, human immunodeficiency virus; JRA, juvenile rheumatoid arthritis (Still disease); SLE, systemic lupus erythematosus.

From Kliegman RM, Greenbaum LA, Lye PS: Practical strategies in pediatric diagnosis and therapy, ed 2, Philadelphia, 2004, Elsevier, p 863.