Clinical Analysis: 52-Year-Old Male - Back Pain + Radiculopathy + CBC Abnormalities

Interpreting the CBC

Differential Diagnosis - Causes

1. Hematological Malignancies (HIGHEST PRIORITY)

• MDS presents with pancytopenia due to ineffective hematopoiesis
• Eosinophilia is seen in AML-M4Eo (inv(16)) and MDS with eosinophilia
• Back pain/radiculopathy can result from bone marrow infiltration or extramedullary disease
• Harrison's (2025) lists MDS, myelofibrosis, aleukemic leukemia, PNH, and hairy cell leukemia as key causes of pancytopenia with cellular bone marrow

• Aleukemic leukemia is specifically listed as a cause of pancytopenia with both hypocellular and cellular bone marrow
• Bone pain and spinal involvement are common
• AML-M4 with eosinophilia is a recognized entity

• Bone marrow infiltration by lymphoma causes pancytopenia
• Harrison's notes that lymphoma, myeloma, breast, lung, and prostate are common causes of spinal cord compression and back pain/radiculopathy from vertebral metastasis/epidural involvement
• Vertebral metastases present with pain that worsens with movement and classically awakens patients at night

• Myeloproliferative HES (Fip1L1-PDGFRα fusion, JAK2, FGFR1 mutations) can show anemia, thrombocytopenia, splenomegaly, bone marrow cellularity >80%, and dysplastic eosinophils
• Peripheral neuropathy is a recognized extrapulmonary manifestation
• Harrison's notes this occurs predominantly in men aged 20-50

• May show thrombocytopenia, eosinophilia, and nondiagnostic bone marrow

2. Aplastic Anemia

• Acquired immune aplastic anemia causes pancytopenia from marrow failure
• Constitutional causes (Fanconi anemia, telomere biology disorders) are less likely at 52 years but possible
• Hypoplastic MDS overlaps significantly with aplastic anemia

3. Chronic Arsenic Poisoning (MUST NOT MISS)

• This combination of pancytopenia + eosinophilia + neuropathy (presenting as radiculopathy/back pain) is a textbook triad of chronic arsenic poisoning
• Look for: Mees lines on nails, raindrop pigmentation, hyperkeratosis of palms/soles, occupational or environmental exposure history
• Diagnosis: 24-hour urine arsenic (>100 µg/g creatinine is significant), hair/nail arsenic levels, nerve conduction studies showing distal sensorimotor axonopathy

4. Parasitic / Infectious Causes

• Visceral Leishmaniasis (Kala-azar): pancytopenia + massive splenomegaly; eosinophilia can be seen
• Malaria: hemolysis + thrombocytopenia; chronic infection may cause bone marrow suppression
• Tuberculosis: listed explicitly in Harrison's as causing pancytopenia with cellular bone marrow, also causes vertebral disease (Pott's spine = back pain + radiculopathy)
• Brucellosis: causes pancytopenia + spondylitis (classic cause of back pain in endemic areas)

5. Other Systemic Causes

• Systemic Lupus Erythematosus: causes pancytopenia with cellular marrow + neuropathy
• Hypersplenism (from cirrhosis, portal hypertension)
• B12/Folate deficiency: megaloblastic pancytopenia + peripheral neuropathy (mimics radiculopathy)
• HIV infection: directly listed as cause of pancytopenia with cellular marrow
• Sarcoidosis: can cause pancytopenia + peripheral neuropathy

Priority Diagnostic Framework

Immediate (Emergency) Workup

1. Peripheral blood smear - look for blast cells, dysplastic cells, parasites, hypersegmented neutrophils, basophilic stippling
2. Reticulocyte count - to distinguish hypoproliferative vs. hemolytic/destructive
3. Bleeding assessment - platelets 37,000 puts patient at risk of spontaneous bleeding
4. MRI spine (urgent) - rule out epidural compression/metastatic disease (per Harrison's: "If spinal cord compression is suspected, imaging should be obtained promptly; image entire length of the spine")

Core Laboratory Investigations

Bone Marrow Biopsy + Aspirate (Mandatory)

• This is the cornerstone investigation for all causes of pancytopenia
• Will differentiate aplastic anemia, MDS, leukemia, lymphoma, HES, granulomatous infection, leishmaniasis, myelofibrosis
• Send for cytogenetics, flow cytometry, trephine histology, culture (TB, fungi)

Nerve Conduction Studies

• To characterize neuropathy - axonal sensorimotor neuropathy suggests arsenic, B12 deficiency; demyelinating pattern suggests other causes

Management

1. Immediate Supportive Care

• Platelet transfusion if active bleeding or platelets <10,000 (at 37,000 with active bleed or procedure, transfuse)
• Red cell transfusion if symptomatic anemia (Hb 12 is mild but monitor)
• Infection precautions: WBC 2,200 with neutropenia puts patient at risk - check ANC (absolute neutrophil count); if ANC <500, reverse isolation + empirical antibiotics if febrile
• Pain management for radiculopathy - NSAIDs with caution given thrombocytopenia; consider opioids or gabapentin

2. If Malignancy/Spinal Cord Compression Confirmed

• Dexamethasone 10 mg IV immediately if spinal cord compression suspected, then 4 mg every 6 hours
• Urgent MRI spine for full evaluation
• Neurosurgical/radiation oncology referral for decompression or radiotherapy
• Specific therapy based on tumor type (chemotherapy for leukemia/lymphoma)

3. If Aplastic Anemia

• Triple therapy (FDA-approved since 2018): Horse ATG + Cyclosporine + Eltrombopag
  • Induces hematologic recovery in 70-80% of patients
  • Eltrombopag 150 mg/day orally for 6 months
  • Cyclosporine adjusted by blood levels; monitor for nephrotoxicity
  • Methylprednisolone with ATG to prevent serum sickness
• Allogeneic stem cell transplant: preferred in younger patients with matched sibling donor; equivalent survival to immunosuppression overall
• At age 52, immunosuppression is generally preferred over transplant

4. If MDS

• Risk stratification by IPSS-R score
• Low-risk: supportive care, erythropoiesis-stimulating agents, lenalidomide (del5q)
• High-risk: azacitidine or decitabine (hypomethylating agents); allogeneic SCT for eligible patients

5. If HES - Myeloproliferative Variant

• Imatinib (tyrosine kinase inhibitor): treatment of choice for Fip1L1-PDGFRα positive HES - highly effective
• Corticosteroids: less effective in myeloproliferative variant (<50% response)
• Mepolizumab (anti-IL-5): FDA-approved for HES - steroid-sparing, reduces relapses
• Hydroxyurea, interferon-α as alternatives
• Benralizumab (anti-IL-5Rα): investigational but promising

6. If Arsenic Poisoning

• Remove from source of exposure (occupational/environmental)
• Supportive care + fluid repletion
• Chelation therapy: Dimercaprol (BAL) for acute severe poisoning; DMSA (succimer) for subacute/chronic poisoning
• In chronic inorganic arsenic intoxication, clear benefit of chelation is not established
• Bone marrow suppression and ECG abnormalities are generally reversible after exposure ceases
• Neuropathy may be permanent in severe cases

7. If Infectious Cause (Brucellosis/TB/Leishmaniasis)

• Brucellosis: Doxycycline + Rifampicin x 6 weeks (or streptomycin combination); also treat spondylitis
• TB spondylitis: Standard 4-drug RHEZ regimen; surgical stabilization if needed
• Visceral Leishmaniasis: Liposomal amphotericin B (drug of choice), or miltefosine

Key Clinical Pearl for This Case

1. Hematological malignancy with spinal involvement (lymphoma, MDS, AML-M4Eo) - must rule out urgently with MRI spine and bone marrow biopsy
2. Chronic arsenic poisoning - unique triad of neuropathy + pancytopenia + eosinophilia; enquire about occupational history, look for skin/nail signs
3. Myeloproliferative HES - check tryptase, B12, FIP1L1-PDGFRA fusion
4. TB/Brucella spondylitis - if from endemic area, fever, weight loss
5. B12 deficiency - megaloblastic pancytopenia + subacute combined degeneration mimicking radiculopathy