Malignant nodes are generally firm, rubbery, and matted. They are usually not tender or erythematous. Occasionally, a rapidly growing malignant node may be tender. Nodes due to infection or inflammation are generally warm, tender, and fluctuant. If infection is considered to be the cause of the adenopathy, it is reasonable to perform a 2-week trial of antibiotic therapy. Failure to produce a reduction in the size of the lymph node within this period is an indication for careful observation. If the size, location, and character of the node suggest malignant disease, the node should be biopsied.

Lymphadenopathy is either localized (one region affected) or generalized (two or more noncontiguous lymph node regions involved). Although localized lym-phadenopathy is generally due to local infection in the region drained by the particular lymph nodes, it may also be due to malignant disease, such as Hodgkin disease or neuroblastoma. Lymphadenopathy may initially be localized and subsequently become generalized. Table 12-2 outlines the causes of lymphadenopathy.

Table 12-2. Causes of Lymphadenopathy I. Nonspecific reactive hyperplasia (polyclonal)

II. Infection

A. Bacterial:

Staphylococcus, streptococcus, anaerobes, tuberculosis, atypical mycobacteria, bartonella henselae, brucellosis, salmonella typhi, diphtheria, C. trachomatis (lymphogranuloma venereum), calymmatobacterium granulomatis, francisella tularensis

Epstein-Barr virus, cytomegalovirus, adenovirus, respiratory syncytial virus, influenza, coxsackie virus, rubella, rubeola, varicella, HIV, herpes simplex II

C. Protozoal:

Toxoplasmosis, malaria, trypanosomiasis

D. Pirochetal:

Syphilis, rickettsia typhi (murine typhus)

E. Fungal:

Coccidioidomycosis (valley fever), histoplasmosis, cryptococcus, aspergillosis

F. Postvaccination: Smallpox, live attenuated measles, DPT, Salk vaccine, typhoid fever

III. Connective tissue disorders

A. Rheumatoid arthritis

B. Systemic lupus erythematosus

IV. Hypersensitivity states

A. Serum sickness

B. Drug reaction (e.g., Dilantin, mephenytoin, pyrimethamine, phenylbutazone, allopurinol, isoniazid, antileprosy and antithyroid medications)

V. Lymphoproliferative disorders (Chap. 13)

A. Angioimmunoblastic lymphadenopathy with dysproteinemia

B. X-linked lymphoproliferative syndrome

C. Lymphomatoid granulomatosis

D. Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease)

E. Castleman disease (benign giant lymph node hyperplasia, angiofollicular lymph node hyperplasia)

F. Autoimmune lymphoproliferative syndrome (ALPS) (Canale-Smith syndrome)

G. Post-transplant lymphoproliferative disorder (PTLD)

VI. Neoplastic diseases

A. Hodgkin and non-Hodgkin lymphomas

B. Leukemia

C. Metastatic disease from solid tumors: neuroblastoma, nasopharyngeal carcinoma, Rhabdomyosarcoma, thyroid cancer

D. Histiocytosis

1. Langerhans cell histiocytosis

2. Familial hemophagocytic lymphohistiocytosis

3. Macrophage activation syndrome

4. Malignant histiocytosis

VII. Storage diseases

A. Niemann-Pick disease

B. Gaucher disease

C. Cystinosis

VIII. Immunodeficiency states

A. Chronic granulomatous disease

B. Leukocyte adhesion deficiency

C. Primary dysgammaglobulinemia with lymphadenopathy

Table 12-2. Causes of Lymphadenopathy—Cont'd

IX. Miscellaneous causes

A. Kawasaki disease (mucocutaneous lymph node syndrome)

B. Kikuchi-Fujimoto diseasea

C. Sarcoidosis

D. Beryllium exposure

E. Hyperthyroidism aA benign form of necrotising apoptotic lymphadenitis of unknown cause. It is rarely associated with systemic lupus erythematosis and can mimic lymphoma.

The following investigations should be carried out to elucidate the cause of either localized or generalized lymphadenopathy:

1. Thorough history of infection, contact with rodents or cats, and systemic complaints.

2. Careful examination of the lymphadenopathy including size, consistency, mobility, warmth, tenderness, erythema, fluctuation, and location. All the lymph node-bearing areas as outlined above should be carefully examined.

3. Physical examination for evidence of hematologic disease, such as hepatosplenomegaly and petechiae.

4. Blood count and erythrocyte sedimentation rate (ESR).

5. Skin testing for tuberculosis.

6. Bacteriologic culture of regional lesions (e.g., throat).

7. Specific serologic tests for Epstein-Barr virus (EBV), Bartonella henselae, toxoplasmosis, cytomegalovirus (CMV), and human immunodeficiency virus (HIV).

8. Chest radiograph and CT scan (if necessary); abdominal sonogram and CT, if indicated.

9. EKG and echocardiogram if Kawasaki disease is suspected.

10. Lymph node aspiration and culture; helpful in isolating the causative organism and deciding on an appropriate antibiotic when infection is the cause of the lymphadenopathy.

11. Fine-needle aspiration; may yield a definite or preliminary cytologic diagnosis and occasionally obviate the need for lymph node biopsy; it provides limited material in the event flow cytometry is required, and negative results cannot rule out a malignancy because the sample may be inadequate.

12. Bone marrow examination if leukemia or lymphoma is suspected.

13. Lymph node biopsy if:

Initial physical examination and history suggest malignancy.

Laboratory testing is inconclusive and lymph node size is greater than 2.5 cm.

Lymph node persists or enlarges.

Appropriate antibiotics fail to shrink node within 2 weeks.

When lymph node biopsy is performed, the results can be maximized when the following precautions are observed:

1. Upper cervical and inguinal areas should be avoided; lower cervical and axillary nodes are more likely to give reliable information.

2. The largest node should be biopsied, not the most accessible one. The oncologist should select the node to be biopsied in consultation with the surgeon.

3. The node should be removed intact with the capsule, not piecemeal.

4. The lymph node should be sent to the pathologist in sufficient tissue culture medium to prevent the tissue from drying out. The node must not be left in strong light, where it will be subject to heat, and it should not be wrapped in dry gauze, which may produce a drying artifact. Fresh and frozen samples should be set aside for additional studies.

When biopsy is performed, the following studies should be done:

1. Gram stain and culture (bacterial including mycobacterial, viral, and fungal)

2. Light microscopy

3. Immunohistochemical stains (to differentiate tumor types)

4. Flow cytometry (to differentiate cell types in leukemia and lymphoma; e.g., T cell, B cell, pre-B cell)

5. Gene rearrangement studies for the T-cell receptor and the immunoglobulin gene to determine monoclonality in leukemia or lymphoma

6. Electron microscopy.

Once the cause of the lymphadenopathy is ascertained, appropriate management can be undertaken.

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