Eosinophilia with Lymphadenopathy - Differential Diagnoses

1. Hematologic Malignancies (HIGH PRIORITY)

Hodgkin Lymphoma

• The classic association. Eosinophilia is paraneoplastic - Reed-Sternberg cells produce IL-5, stimulating eosinophil production.
• Presents with painless lymphadenopathy, B symptoms (fever, night sweats, weight loss), pruritus.
• Eosinophilia is a recognized histologic feature of the mixed-cellularity subtype.

Peripheral T-Cell Lymphomas (PTCL)

• Paraneoplastic eosinophilia via aberrant IL-5/IL-4 production by neoplastic T cells.
• Subtypes to consider: angioimmunoblastic T-cell lymphoma (AITL) - classic triad of generalized lymphadenopathy, polyclonal hypergammaglobulinemia, and eosinophilia.

Other Lymphomas / Leukemias

• Non-Hodgkin lymphoma (various subtypes)
• T-cell leukemias, pre-B ALL with t(5;14) (IL3-IgH) - where eosinophilia is clonal
• Myeloproliferative neoplasms with PDGFRA/PDGFRB/FGFR1 rearrangements
• CML, mastocytosis
• Source: Henry's Clinical Diagnosis, p. 2418; Goldman-Cecil Medicine, Table 156-2

2. Infections

Helminthic (Most Common Worldwide Cause of Eosinophilia)

Fungal

• Coccidioidomycosis - can cause disseminated disease with mediastinal lymphadenopathy and eosinophilia
• Cryptococcosis - especially in immunocompromised
• Eosinophilia can complicate a wide variety of fungal infections

Other Infections

• HIV (advanced disease)
• Chronic tuberculosis (rare)

3. Drug Reactions

DRESS Syndrome

• Classic drug-induced cause: fever, morbilliform rash, lymphadenopathy (~55% of cases), hepatitis, eosinophilia, atypical lymphocytosis
• Incubation: 2-8 weeks after drug initiation
• Culprits: antiepileptics (phenytoin, carbamazepine, lamotrigine), sulfonamides, allopurinol, minocycline, HAART
• Source: Goldman-Cecil, p. 3821; Kaplan & Sadock's Psychiatry, p. 588

Other Drug Hypersensitivity

• Broad range: antibiotics, NSAIDs, anticonvulsants, antidiabetic agents, chlorpromazine, p-aminosalicylic acid

4. Rare/Specific Entities

Kimura Disease

• Rare, benign, chronic inflammatory disorder predominantly in young Asian males
• Classic triad: subcutaneous masses (head/neck), lymphadenopathy, marked eosinophilia + elevated IgE
• Lymph nodes show reactive follicular hyperplasia and extensive eosinophilia with microabscesses
• Source: Comprehensive Clinical Nephrology, p. 3893; Sabiston Surgery, p. 1656

Angioimmunoblastic T-Cell Lymphoma (AITL)

• Generalized lymphadenopathy, polyclonal gammopathy, autoantibodies, autoimmune hemolytic anemia, immune thrombocytopenia, and peripheral eosinophilia - considered under PTCL above but warrants explicit mention
• Source: Dermatology, p. 2554

Hypereosinophilic Syndrome (HES)

• Defined as persistent hypereosinophilia (>1500/uL on 2+ occasions) with end-organ damage attributable to eosinophilia
• Subtypes: myeloid (FIP1L1-PDGFRA), lymphoid (aberrant T-cell clone producing IL-5), idiopathic, familial
• Lymphadenopathy + splenomegaly can be seen; should prompt bone marrow biopsy and flow cytometry
• Source: Goldman-Cecil Medicine, p. 97-201

5. Autoimmune and Immunologic Disorders

Diagnostic Approach Summary

1. Hematologic workup first: CBC + differential, peripheral smear, LDH, uric acid, serum B12 and tryptase (elevated in myeloid HES), flow cytometry for T/B-cell clonality
2. Lymph node biopsy: mandatory if malignancy suspected - do not delay
3. Infection screen: stool O&P x3, serology for Toxocara/Strongyloides/filarial, travel history
4. Drug history: any drug within the last 8 weeks
5. Imaging: CT chest/abdomen/pelvis for lymph node distribution and organomegaly
6. Bone marrow biopsy if peripheral eosinophil count >5000/uL or dysplastic eosinophils on smear, or if myeloid disorder suspected