A ‘drumstick’ (Barr body) appears on the nucleus of a proportion of the neutrophils in normal females and is caused by the presence of two X chromosomes.
In May–Hegglin anomaly the neutrophils contain basophilic inclusions of RNA (resembling Döhle bodies) in the cytoplasm. There is an associated mild thrombocytopenia with giant platelets. Inheritance is autosomal dominant.
Pelger-Huët cells, seen in the benign congenital abnormality (autosomal dominant), also occur in patients with acute myeloid leukaemia or myelodysplasia.
The Chédiak–Higashi syndrome is inherited in an autosomal recessive manner, and there are giant granules in the neutrophils, eosinophils, monocytes and lymphocytes, accompanied by neutropenia, thrombocytopenia and marked hepatosplenomegaly.
Abnormal leucocyte granulation or vacuolation is seen in patients with rare mucopolysaccharide disorders (e.g. Hurler’s syndrome).

Leucocytosis

The total leukocyte count is commonly extremely high with CML (median 100000/μL in some series), but counts above 100000/μL are rare and above 150000/μL virtually unheard of with leukemoid reaction.

CML almost always have some degree of absolute basophilia and eosinophilia, but infection and glucocorticoid excess induce eosinopenia. (When the leukocyte count is 100,000/mm 3 , realize that 2% to 3% basophils is a substantial absolute increase.)
Prominent teardrops RBCs point toward MPN.
Splenomegaly is unusual with leukemoid reaction.
LAP score: high in LR and low in CML.
Most patients with leukemoid reaction are encountered very ill in the hospital with obvious underlying illnesses (e.g., sepsis, organ rejection). Prior WBC counts, which are often available, demonstrate normal WBC counts until the recent onset of acute illness. This contrasts with CML, typically presenting in outpatients with hypermetabolism (weight loss, sweats, low-grade fever), symptoms referable to splenomegaly, or frequently asymptomatic.
In patients with leukemoid reaction, a disproportionate number have infection with Clostridium difficile, an organism that elicits a vigorous neutrophil response. Leukemoid reactions may be associated with solid tumors, sometimes due to paraneoplastic production of colony-stimulating factor or other cytokines, or to particularly aggressive tumors with necrotic areas.

Leukopenia

Hodgkin lymphoma is associated with a variety of white cell abnormalities, including eosinophilia, monocytosis and leukopenia.