What is the significance of teardrop cells (dacrocytes) on the peripheral smear of my patient with newly-discovered pancytopenia?

The presence of teardrop cells (dacrocytes) (Figure below) in the peripheral blood, named for their tear drop shape, is a prominent feature of myelophthisic (marrow infiltrative) conditions, including myelofibrosis, hematologic malignancies, cancer metastatic to the bone marrow, and granulomatous diseases. Teardrop cells may also be seen in beta-thalassemia, autoimmune and microangiopathic hemolytic anemia and severe iron deficiency (1-4).

 
When evaluating patients with leucoerythroblastic smears (defined by the presence of early myeloid and erythroid forms), the presence of teardrop cells can be helpful in distinguishing often malignant marrow infiltrative conditions from a benign reactive process.  Conditions where teardrop cells are seen with high frequency may also have extramedullary hematopoiesis, particularly in the spleen (1,2).

 
The mechanism of tear drop cell formation may be multifactorial but appears to involve distortion of the red cells as they pass through marrow or splenic sinusoids. Teardrop cells resulting from conditions such as cancer metastatic to the bone marrow likely involve primarily a marrow origin of the cells whereas primary myelofibrosis with prominent extramedullary hematopoiesis include a splenic mechanism of tear drop cell formation (2).

 
Supporting the possible splenic contribution to teardrop cell formation is the observation that teardrop cells may be reduced in number or eliminated entirely after splenectomy in patients with myelofibrosis and autoimmune hemolytic anemia (1,4).

Teardrop

Figure. Teardrop cells

References

1. DiBella NJ, Sliverstein MN, Hoagland HC. Effect of splenectomy on teardrop-shaped erythrocytes in agnogenic myeloid metaplasia. Arch Intern Med 1977; 137: 380-381. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/586447
2. Gutgemann I, Heimpel H, Nebe CT. Significance of teardrop cells in peripheral blood smears. J Lab Med 2014; DOI: 10.1515/labmed-2014-0005 https://www.researchgate.net/publication/272430111_Significance_of_teardrop_cells_in_peripheral_blood_smears
3. Korber C, Wolfler A, Neubauer M, Robier Christoph. Red blood cell morphology in patients with β-thalassemia minor. J Lab Med 2016-12-10 | https://www.researchgate.net/publication/311564128_Red_blood_cell_morphology_in_patients_with_b-thalassemia_minor DOI: https://doi.org/10.1515/labmed-2016-0052
4. Robier C, Klescher D, Reicht G,Amouzadeh-Ghadikolai O, Quehenberger F, Neubauer M. Dacrocytes are a common morphologic feature of autoimmune and microangiopathic haemolytic anaemia. Clin Chem Lab Med. 2015;53:1073-6. https://www.ncbi.nlm.nih.gov/pubmed/25503671

Contributed by Tom Spitzer, MD, Director of Cellular Therapy and Transplantation Laboratory,  Massachusetts General Hospital, Boston, MA.
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What is the significance of teardrop cells (dacrocytes) on the peripheral smear of my patient with newly-discovered pancytopenia?

How should I interpret high serum vitamin B12 levels in my patient with anemia?

High serum B12 levels, aka hypercobalaminemia (HC),  is not rare among hospitalized patients with 1 study reporting “high” (813-1355 pg/ml) and “very high” (>1355 pg/ml) serum B12 levels in 13 and 7% of patients, respectively1.

Common causes include excess B12 intake, solid neoplasms (particularly, hepatocellular carcinoma and metastatic neoplastic liver disease), blood disorders (eg, myelodysplastic syndrome, CML, and acute leukemias, particularly AML3), and other liver diseases, including alcohol-related diseases as well as acute and chronic hepatitis.  Other inflammatory states and renal failure have also been reported2.  

Paradoxically, even in the presence of HC, a functional B12 deficiency may still exist. This may be related to poor B12 delivery to cells due to its high binding by transport proteins transcobalamin I and III in HC which may in turn cause a decrease in the binding of B12 to transcobalamin II, a key player in B12 transport to tissues2.  In this setting, elevated serum methylmalonic acid and homocysteine levels may be helpful.

References:

  1. Arendt JFB, Nexo E. Cobalamin related parameters and disease patterns in patients with increased serum cobalamin levels. PLoS ONE 2012;9:e45979. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0045979
  2. Andres E, Serraj K, Zhu J. et al. The pathophysiology of elevated vitamin B12 in clinical practice. Q J Med 2013;106:505-515.https://www.ncbi.nlm.nih.gov/pubmed/23447660
How should I interpret high serum vitamin B12 levels in my patient with anemia?