Infectious Causes of Dry-Tap Bone Marrow with Hypercellular Trephine Biopsy
The most common infectious causes of a dry-tap bone marrow aspirate with hypercellular trephine biopsy are acute leukemia (32.8% of dry taps), followed by parasitic infections (particularly leishmaniasis), tuberculosis, and fungal infections.
Primary Infectious Etiologies
While acute leukemia is the leading cause of dry taps overall 1, when specifically considering infectious pathology that produces this pattern, the following organisms are most relevant:
Parasitic Infections
- Leishmaniasis (Leishmania donovani) is the most frequently diagnosed parasitic infection on bone marrow examination, accounting for 65.5% of infectious diagnoses 2 and 26.9% of infection-related bone marrow cases 3
- The organism causes marrow hypercellularity with prominent histiocytes, plasmacytosis, and erythroid hyperplasia
- LD bodies can be identified in bone marrow aspirate when adequate material is obtained 4
- Other parasites include microfilaria and Plasmodium species 3
Mycobacterial Infections
- Mycobacterium tuberculosis causes granulomatous inflammation with marrow fibrosis, leading to dry tap
- Trephine biopsy shows granulomas in 70% of pyrexia of unknown origin cases 5
- Caseating necrosis and giant cell formation are characteristic histological findings 6
- Acid-fast bacilli may be identified on Ziehl-Neelsen staining 6
- Nontuberculous mycobacteria (including BCG and M. avium intracellulare) occur in immunocompromised patients 6, 2
Fungal Infections
- Histoplasmosis accounts for 10.3% of bone marrow infections 2
- Other fungi include Aspergillosis, Blastomycosis, Coccidiomycosis, and Cryptococcosis 6, 2
- Fungal infections cause granulomatous changes without caseation 6
- Risk factors include immunosuppression, steroid use, neutropenia, and chronic granulomatous disease 6
Bacterial Infections
- Brucella species cause noncaseating granulomas with gram-negative coccobacilli 6
- In endemic regions, Brucella accounts for 24-34% of vertebral osteomyelitis cases 6
- Hansen's disease (leprosy) can infiltrate bone marrow 2
Diagnostic Approach
When encountering a dry tap with hypercellular biopsy, immediately send trephine biopsy material for:
- Bacterial cultures (aerobic and anaerobic)
- Mycobacterial stain and culture with nucleic acid amplification testing
- Fungal stain and culture
- Brucella culture (if epidemiologically relevant)
- Histopathology to identify granulomas, organisms, and architectural patterns
Key Morphological Clues on Trephine Biopsy
The following findings should alert you to infectious etiology 3, 4:
- Plasmacytosis (67.3% of infection cases)
- Hemophagocytosis (32.6% of cases)
- Granulomas (17.3% of cases, with 9.6% AFB-positive)
- Prominent histiocytes
- Erythroid hyperplasia (50% of cases)
- Reactive lymphocytosis or monocytosis
Critical Pitfall
Do not attribute a dry tap solely to technical error. Only 16% of dry taps are due to faulty technique when the trephine biopsy is adequate 1. An underlying pathology—most commonly acute leukemia (32.8%) or infectious disease (particularly leishmaniasis, tuberculosis, or fungal infection)—is identified in 84% of cases 1.
Geographic and Host Considerations
- In endemic regions (Turkey, Greece, Mediterranean), consider Brucella and M. tuberculosis as common causes 6
- In immunocompromised patients (HIV, steroids, chronic granulomatous disease), prioritize fungal pathogens and nontuberculous mycobacteria 6
- Molecular diagnostics (16S ribosomal RNA PCR) enhance sensitivity, particularly for Brucella and mycobacterial infections after prior antibiotic exposure 6
When Smears from Needle Material Are Available
Even with a dry tap, smears prepared from material left within the aspiration needle can provide diagnostic information to complement or establish the diagnosis 7. Look for LD bodies, acid-fast bacilli, or fungal elements.