Chapter 35: Basophils and Mast Cells and Their Diseases

BASOPHILIA

• Normal basophil count is 0.015 to 0.08 × 10⁹/L.

• The causes of basophilia are listed in Table 35–1.

• An increase in the absolute basophil count among other blood cell abnormalities may be a useful sign of a chronic clonal myeloid disease (see Table 35–1).

• In chronic myelogenous leukemia (CML), an increased absolute basophil count occurs in virtually all patients.

• De novo acute basophilic leukemia is very rare, but marrow basophilia may be associated uncommonly with other subtypes of acute myelogenous or acute promyelocytic leukemia (see Table 35–2).

• Basophils in acute or chronic clonal myeloid diseases are derived from the malignant clone and occasionally may cause symptoms of histamine release (flushing, pruritus, hypotension) or severe peptic ulcer disease reflecting hypersecretion of gastric acid and pepsin.

BASOPHILOPENIA

• The causes of basophilopenia are listed in Table 35–1.

MAST CELLS

• Mast cells are produced in the marrow, transit the blood to the tissues where they reside. They cannot be identified in transit in the blood of healthy individuals by standard techniques.

• Mast cells contain mediators that may be preformed in granules (e.g., histamine, heparin, and chemotactic factors) or newly formed (e.g., arachidonic acid metabolites, such as prostaglandin D₂ and leukotrienes).

REACTIVE MASTOCYTOSIS

• An increased number of mast cells may be seen in any tissue involved in a hypersensitivity reaction.

• An increased number may be seen in the lymph nodes and marrow as a reaction to a variety of benign and malignant tumors.

BENIGN MAST CELL DISEASES