Cytochemical "normal" and "abnormal" eosinophils in acute leukemias

Cocktail of Periodic Acid-Schiff and Papanicolaou: Novel staining technique for the identification of leukemic eosinophils - A pilot study

Background

Tissue eosinophilia may be caused due to reactive, neoplastic or idiopathic reasons. Reactive eosinophils in allergic and inflammatory conditions are transient and recruited from the circulation in response to various stimuli, whereas neoplastic eosinophils of leukemias and hematological malignancies are involved in the pathogenesis of the disease. The differentiation of reactive from neoplastic eosinophils has a serious implication on the treatment and prognosis of diseases. However, both these types of eosinophils display variation in morphology and staining characteristics in routine histopathology leading to a diagnostic dilemma.

Aim

The aim of this study is to evaluate the efficacy of special stains for the demonstration of eosinophils in normal/reactive lesions and leukemias.

Methodology

A retrospective study comprising twenty histologically diagnosed cases each of reactive oral lesions and leukemias were obtained from institutional archives. These tissue sections were subjected to staining with routine and special stains - Carbol chromotrope, Congo red, Leishman's stain, Periodic Acid-Schiff-papanicolaou (PAS-PAP) and PAS. Statistical analysis was performed using Pearson's Chi-square test to compare the various parameters in the evaluation of the staining efficacy.

Results

Carbol chromotrope and Congo red staining showed increased staining efficacy in normal/reactive eosinophils while PAS-PAP followed by PAS and Leishman's stain showed enhanced features such as homogenicity, specificity, increased staining intensity, enhanced nuclear and cytoplasmic details in leukemic eosinophils.

Conclusion

Combined PAS-PAP is a novel and cost-effective staining technique in differentiating reactive and leukemic eosinophils. It is significant in recognizing leukemic eosinophils of routine biopsies and alerts the clinician to rule out any underlying malignancies.

Extramedullary blast crisis in chronic myeloid leukemia

Among 235 patients with CML we reviewed 91 patients with BC diagnosed between 1980 and 1995; 15 of the 91 (16%) developed extramedullary disease (EMD). The sites involved were the lymph nodes (13/15), CNS (1/15) and suborbital mass (1/15). The appearance of EMD was associated with chronic phase (CP) features in the bone marrow in 3/15 cases, with accelerated phase (AP) in 3/15 and with BC in 9/15. 11/15 (73%) cases of EMD were classified as myeloid (My-EMD) and 4/15 as lymphoid-type (Ly-EMD): three B-phenotype and one T-phenotype. All Ly-EMD cases were treated with vincristine, daunorubicin and prednisone and obtained complete remission (CR). Cases of My-EMD were treated with daunorubicin and cytosine arabinoside, of which only 1/11 achieved CR. We suggest that in EMD also, the type, lymphoid or myeloid, of BC has a bearing on treatment response and prognosis: Ly-EMD is more responsive to treatment and has longer survival than My-EMD.

Cytophagocytosis by the blast cells in acute myeloid leukemia

The occurrence of cytophagocytosis as spontaneous ingestion of cells by blast cells has been poorly investigated in acute leukemia. Cytophagocytosis by blasts in acute myeloid leukemia (AML) was observed in eleven patients who represent 1% of AML cases seen in our institution (one M1, two M2, four M4 and four M5). Prominent features of cytophagocytosis by AML blasts are particularly evident in leukemias involving monocytic cells and were more obvious in the bone marrow than the peripheral blood. AML of the monocytic type with cytophagocytosis are frequently associated with cytogenetic aberrations involving chromosomes 8 and 16. Finally the poor outcome of AML patients with cytophagocytosis and their poor response to therapy and short survival is stressed.

Induction of eosinophilic colonies by interleukin-5 on acute myeloblastic leukaemic cells

The effect of interleukin-5 (IL-5) on blast colony formation of acute myeloblastic leukaemia (AML) cells was studied. IL-5 showed a weak but significant colony stimulatory effect in one out of six cases studied. IL-5 induced eosinophilic colony growth in this case, and chromosomal and histochemical analyses strongly suggested that these eosinophilic colonies were derived from leukaemic blast progenitor cells. To our knowledge, this is the first report that IL-5 induces eosinophilic colonies on fresh AML cells. A possible induction of differentiation of AML blast cells by IL-5 is suggested.

Dysplastic eosinophils in three patients with acute promyelocytic leukaemia

Three cases of acute promyelocytic leukaemia (M3) with dysplastic eosinophils are reported. Promyelocytes from these cases showed classical features of hypergranular acute promyelocytic leukaemia. All the cases had minimal organomegaly and disturbances of coagulation were minimal. All the cases were associated with dysplastic eosinophils in the marrow but very few of these eosinophils were found in peripheral smear. One of the three patients presented with a mass in the vertebral column, a feature not uncommonly seen in a variant form of AML-M2 with eosinophilia. Dysplastic eosinophils appear to arise from leukaemic clone itself. These three cases probably represent hitherto undescribed morphological variant of acute promyelocytic leukaemia where leukaemic cells show limited differentiation capability to dysplastic eosinophils.

Acute nonlymphocytic leukemia with eosinophilic differentiation

Four cases of de novo acute nonlymphocytic leukemia (ANLL) with early eosinophilic differentiation are described. The clinical course did not differ from that of the usual forms of ANLL. Morphologic and cytochemical features that can support this diagnosis are discussed. Particularly, the cyanide-resistant peroxidase stain appeared to be a specific marker of eosinophilic differentiation. Acute eosinophilic leukemia is a distinct entity, and this unusual subtype of ANLL can be set apart from other forms of ANLL characterized by hypereosinophilia.

Association of an inversion of chromosome 16 with abnormal marrow eosinophils in acute myelomonocytic leukemia. A unique cytogenetic-clinicopathological association

We identified 18 patients with an inversion of chromosome 16, inv(16)(p13q22), among 308 patients with newly diagnosed acute nonlymphocytic leukemia. Each of these 18 patients had acute myelomonocytic leukemia (M4 subtype) and eosinophils with distinctly abnormal morphology, cytochemical staining, and ultrastructure. These eosinophils constituted from 1 to 33 per cent of the nucleated marrow cells. In our series, every patient with acute myelomonocytic leukemia and abnormal eosinophils also had an abnormal chromosome 16. This subgroup of M4 patients had a good response to intensive therapy designed to induce remission; 13 of 17 treated patients entered a complete remission, and 10 remain in first remission. Thus, patients with an inversion of chromosome 16 appear to represent a unique cytogenetic-clinicopathological subtype of acute nonlymphocytic leukemia with a favorable prognosis.

Platelet satellitism to basophils in a patient with chronic myelocytic leukaemia

Platelet satellitism to basophil granulocytes was observed in a patient with chronic myelocytic leukaemia. This phenomenon occurred with peripheral basophil cells obtained from venous blood anticoagulated with EDTA. Previous reports have demonstrated platelet satellitism to polymorphonuclear neutrophils and monocytes but not to other types of white blood cells. The cause of the platelet satellitism in this CML case remains unclear. It is suggested that this rare phenomenon should be considered in evaluating the platelet number in CML.

Adenosine deaminase activity in acute lymphoblastic leukaemia: cytochemical, immunological and clinical correlations

Adenosine deaminase (ADA) activity has been assessed in lymphoid cells of 23 patients with acute lymphoblastic leukaemia (ALL) in order to attempt a further characterization of ALL cells in addition to the well known cytochemical and immunological T and B lymphoid cell markers. ADA activity did not show any correlation with the immunological characterization of the patients investigated; in fact a wide range of ADA activity was observed with levels ranging from 0 to 32 U in T-ALL patients and nearly similar values (from 1.8 to 36 U) in the group of non T--non B ALL cases. Normal values ranged from 2 to 5 U (mean 2.9 U; s.d. +/- 0.8). Some cytochemical patterns (acid phosphatase and PAS) appeared well correlated with T markers of lymphoid cells, whereas they showed no significant relationship with ADA activity.