Dacryocytes are a common morphologic feature of autoimmune and microangiopathic haemolytic anaemia

Dacryocytes are teardrop-shaped erythrocytes which are most frequently observed in peripheral blood smears of patients with primary or secondary myelofibrosis as well as malignant infiltrative disorders of the bone marrow. Dacryocytes have rarely been described in blood smears of patients with autoimmune (AIHA) and microangiopathic haemolytic anaemia (MAHA). The clear prevalence of dacryocytes in AIHA and MAHA is unknown.

We compared the dacryocyte counts in blood smears stained according to the May-Grünwald-Giemsa technique between 20 subjects with AIHA and MAHA with those from 21 controls. The dacryocytes, defined as erythrocytes tapered to a point at one end, were counted as cells per 20 high power fields (HPF) at 630-fold magnification.

In AIHA, MAHA and controls, dacryocytes were found in 89%, 91% and 19% of the slides, respectively. The rate of dacryocyte positivity and the dacryocyte counts between haemolytic anaemias and controls differed statistically highly significant (p<0.0001).

The results of this study indicate that dacryocytes are commonly apparent in blood smears of patients with AIHA and MAHA. Knowledge of this frequent feature may be beneficial in clinical routine diagnosis.