What do tear drop forms on a blood smear indicate?

Teardrop Cells (Dacryocytes) on Blood Smear: Clinical Significance

Teardrop-shaped red blood cells (dacryocytes) on a peripheral blood smear most commonly indicate bone marrow fibrosis or infiltrative marrow disorders, but they are also frequently seen in autoimmune hemolytic anemia and microangiopathic hemolytic anemia, particularly when associated with splenomegaly and extramedullary hematopoiesis.

Primary Diagnostic Considerations

Myelofibrosis and Bone Marrow Infiltration

• Myelodysplastic syndromes (MDS) with bone marrow fibrosis represent the classic association with teardrop cells, often accompanied by a leukoerythroblastic blood picture 1
• Primary myelofibrosis (PMF), including prefibrotic stages, characteristically shows teardrop poikilocytosis even before significant fibrosis develops 2
• The spleen plays a critical role in teardrop cell formation in agnogenic myeloid metaplasia, with splenectomy resulting in a fourfold decrease in teardrop cells 3
• MDS/myeloproliferative neoplasm (MPN) overlap syndromes can present with teardrop cells alongside other dysplastic features 4

Hemolytic Anemias

• Autoimmune hemolytic anemia (AIHA) shows dacryocytes in 89% of cases, with the spleen and extramedullary hematopoiesis contributing to their formation 5, 6
• Microangiopathic hemolytic anemia (MAHA) demonstrates dacryocytes in 91% of cases, significantly more than in controls (19%) 6
• Resolution of splenomegaly or splenectomy leads to disappearance of teardrop cells in hemolytic anemia, confirming the splenic contribution 5

Diagnostic Approach

Initial Blood Smear Evaluation

• Quantify teardrop cells systematically (count per 1,000 RBCs or per 20 high-power fields) to establish clinical significance 6, 3
• Look for accompanying features that narrow the differential:
  • Leukoerythroblastic picture (nucleated RBCs and immature granulocytes) suggests marrow infiltration or fibrosis 1, 2
  • Schistocytes point toward MAHA rather than marrow pathology 7
  • Spherocytes and polychromasia suggest AIHA 5
  • Dysplastic features (pseudo-Pelger-Huët cells, hypogranulation) indicate MDS 4

Clinical Context Assessment

• Splenomegaly presence and degree is critical: massive splenomegaly suggests myelofibrosis, while moderate splenomegaly with hemolysis suggests AIHA or extramedullary hematopoiesis 5, 1, 2
• Complete blood count patterns help differentiate:
  • Cytopenias with dysplasia suggest MDS 4
  • Leukocytosis with monocytosis suggests CMML (MDS/MPN overlap) 4
  • Anemia with reticulocytosis suggests hemolytic process 7

Definitive Diagnostic Testing

• Bone marrow examination (aspiration and biopsy with reticulin stain) is essential when myelofibrosis or MDS is suspected 4, 1, 2
  • Prefibrotic myelofibrosis shows increased cellularity, abnormal megakaryocyte clustering, and dysplastic megakaryocytes even without increased reticulin 2
  • MDS with fibrosis demonstrates dysplasia in multiple lineages with variable fibrosis 1
• Direct antiglobulin test (DAT) should be performed when AIHA is suspected based on hemolysis markers 5
• Cytogenetic and molecular testing are necessary for MDS/MPN diagnosis, as chromosomal abnormalities occur in up to 80% of MDS patients 4

Critical Clinical Pitfalls

Common Misinterpretations

• Do not assume all teardrop cells indicate myelofibrosis: nearly 90% of AIHA and MAHA cases show dacryocytes, which may lead to unnecessary bone marrow biopsies if hemolysis is not considered 6
• Prefibrotic myelofibrosis lacks reticulin increase initially but still produces teardrop cells, so absence of fibrosis on biopsy does not exclude early PMF 2
• Splenectomy dramatically reduces teardrop cells in both myelofibrosis and hemolytic anemia, confirming the spleen's role in their formation regardless of underlying cause 5, 3

Algorithmic Decision-Making

1. If teardrop cells + hemolysis markers (elevated LDH, low haptoglobin, reticulocytosis): Check DAT for AIHA; evaluate for schistocytes suggesting MAHA 5, 6
2. If teardrop cells + cytopenias + splenomegaly without hemolysis: Proceed to bone marrow biopsy to evaluate for myelofibrosis or MDS 1, 2
3. If teardrop cells + leukocytosis/monocytosis: Consider MDS/MPN overlap syndromes and perform bone marrow examination with molecular testing 4