Acute Monoblastic Leukemia

What is Acute Monoblastic Leukemia?

The interregional form of acute leukemia is observed in 6-8% of adults and 2.6% of children.

Pathogenesis during Acute Monoblastic Leukemia

The clinical picture of this form of leukemia differs little from acute myeloid leukemia, although intoxication and fever are more often expressed. More often complications associated with neutropenia are detected, among which necrotic changes in the mucous membrane of the mouth and pharynx predominate, which is facilitated by the leukemic gum infiltration characteristic of this form of acute leukemia, leading to papillary hypertrophy. Inflammation of the tongue may also be due to neutropenia itself.

In monoblastic acute leukemia, the process is localized mainly in the bone marrow, but certain groups of lymph nodes and the spleen can be enlarged. Often, infiltration of the tonsils and gums develops, and in the late stages of progression, the appearance of infiltrates in all internal organs and leukemids in the skin, on the serous membranes is possible.

Diagnosis of Acute Monoblastic Leukemia

This leukemia is characterized by large blast cells that have a bean-like, with a shallow depression, a structural nucleus with several nucleols. The cytoplasm of such cells is less than that of a monocyte, however, more than that of myeloblast, its color can be of different shades – from gray-blue to intensely blue. Sometimes such cells are found only in the bone marrow, and in the blood there are more mature elements resembling monocytes, sometimes almost indistinguishable from them. There are cases of monoblastic leukemia with neutrophilia in the blood and with a “rejuvenation” of the leukogram to myelocytes. Platelet count is usually reduced.

With monoblastic leukemia in the blood and bone marrow, there may be blast cells with a round nucleus and a narrow rim of the cytoplasm, and only cytochemical features indicate their belonging to elements of a monocytic nature.

The peculiarity of this form of acute leukemia is the cytochemical characteristic of monocytic elements: they give a positive reaction to nonspecific a-naphthyl esterase and a-naphthyl esterase, suppressed by sodium fluoride.

Serum and urine of patients with monoblastic and myelomonoblastic leukemia contain a lot of lysozyme (muramidase) – an enzyme that is found in large quantities in normal monocytes.

In some cases of acute monoblastic and myelomonoblastic leukemia, immunoglobulin G or M may appear in serum. In such cases, scientists using the immunofluorescence method have proved that immunoglobulins are located on leukemia cells (Law et al., 1976).

The frequency of complete improvement in acute monoblastic leukemia in modern treatment is the same as in acute myeloid leukemia – more than 60%.