December 1984, Volume 34, Issue 12

Editorial

T-Lymphoblastic Leukaemia (T-ALL)

Mirza Naqi Zafar  ( Zafar Research and Diagnostic Centre, 7/14 Rimpa Plaza, Clinic Side. M.A. Jinnah Road. Karachi. )

Cases with this association have been reported under different names such as Steinberg sarcoma, childhood lymphoblastic or T-cell lymphoma, lymphoma of the convulated lymphocytes, ALL with an anterior mediastinal mass and acid phosphatase-positive acute lymphoblastic leukaemia. To quote here from an excellant review by Cooke’ : On reviewing the individual clinical and pathological reports it is noticeable that the only feature by which they differ from a similar series of cases of acute leukaemia is by the presence of the mediastinal tumour. Clinical manifestations, blood picture eventual glandular and splenic enlargement, extensive infiltration of the bone marrow, liver and kidneys by non-granular mononuclear cells are identical whether or not a mediastinal mass is present. Cooke1 described the main features of the disease, namely predominance of males over females, an incidence almost always below the age of 30 years (mean 16 years), and in two-thirds of the cases where haematological data were available WBC count was over 100x109/Litre. She also noted that the thymic tumour may precede by several weeks the development of ALL, or that both features may be present ab inito. It is now acknowledged that an initial presentation as an acute leukaemia or with lymphadenopathy but without mediastinal enlargement is also possible2,3,4
The speed with which the leukaemic picture may develop is graphically illustrated by one of Cooke’s cases where a WBC count of 21x109/Litre with 72% neutrophils changed a week later to 140x109/L with 89%lymphoblasts. A high frequency (70%) of leukaemic transformation in children with malignant lymphomas (non-Burkitt type) has been reported5 , particularly in those cases with mediastinal involvement meningeal leukaemia was seen in half of their cases with bone marrow involvement. The marked predominance of males and the higher incidence of T-ALL in older children as compared with Null-ALL has been confirmed by most of th.e recently published series6,7 A’so splenomegaly is a more constant feature in T ALL than Nuft ALLl8.
T-ALL thus appears to be associated with factors known to be of bad prognosis in ALL in general. Meningeal leukaemia, presumably related to the high initial WBC counts. is commonly early event lnteresting observations have been made in relation to the worse prognosis in T-ALL7. The remission rate to conventional ALL treatment was only 40% in i-ALL compared with 89% in other ALL cases. When comparing groups of similar WBC counts and organomegaly (except for mediastinal mass) similar drug schedules resulted in earlier relapses and shorter survivals in T-ALL. thus suggesting an intrinsically more malignant nature for T-cell neoplasm apparantty not accounted for only by the noted differences in WBCs. ALL with a thymic mass appears to have in addition to high WBC at presentation, higher haemoglobin and platelet counts than Null-ALL, thus suggesting a better preservation of the normal bone marrow and that the tumour cells may not have arisen from the bone marrow itself as they seem to in the common type or Null-ALL.
The importance of recognising T-ALL as a distinct clinicopathological and immunological variant of ALL, is emphasised from the fact that in some studies on cell markers in ALL, cases presenting with an anterior mediastinal mass were excluded9, however some months later the same group of workers inJuded sach with positive T-markers as examples of immnuno blastic acute lymphoid leukaemia. It is perbaps only of semantic interest to decide whether the disease ould be considered primarily a leukaemia or a lymphoma and which is the right nomenclature. This in fact may depend on whether the initial diagnosis (which may depend on the presenting clinical features) is made by an histopathologist, a haernatologist or even an immunologist. The almost inevitable development of ALL in patients presenting with thymic tumours, the fact, perhaps equally is that as many will already have ALL at the time of diagnosis, and the knowledge that some may not have a mediastinal mass at all, suggest that the disease should be considered primarily a leukaemic process-hence the suggested name: ‘T-ALL’. As commented above, the leukaemic manifestations are even more florid than in other cases of ALL. The T’ preceding the abbreviation ‘ALL’ is necessary as it denotes the likely thymic origin and the lymphoid nature of the cell target for the malignant process.

References

1. Cooke, J.V. Mediastinal tumour in acute leukaemia; a clinical and roentgenologic study. Am. J. Dis. Child., 1932; 44: 1153.
2. Catovsky, D., Goldman, J.M, Okos, A. et al. T-lymphoblastic leukaemia: a distinct variant of acute leukaemia. Br. Med J. 1974; 2: 623.
3. Kaplan, J., Mastrangelo, R. and Peterson, W.D. Jr. Childhood lymphoblastic lymphoma, a cancer of thymus derived lymphocytes. Cancer Res., 1974;34: 521.
4. Lukes, R.J. and Collins, R.D. Immunologic characterization of human malignant lymphomas. Cancer, 1974; 34:1488.
5. Watanabe, A., Sullivan, M.D., Sutow, W.W. and Wilbur, J. R. Undifferentiated lymphoma, nodular type; meningeal and bone marrow involvement in children. Am. J. Dis. Child., 1973; 125 : 56.
6. Borella, L. and Sen, L. Ereceptors on blasts from untreated acute lymphocytic leukemia (ALL); comparison of temperature dependence of Erosettes formed by normal and leukemic lymphoid cells. J. Immunol., 1975; 114 : 187.
7. Ravindranath. Y., Kaplan, J. and Zeulzer W.W. Significance of mediastinal mass in acute lymphoblastic leukaemia. Pediatrics., 1975; 55 889.
8. Catousky, D. Cell markers in acute lymphoblastic leukaemia and lymphoproliferative disorders. Recent Adv, Haematol, 1977; 2: 201.
9. Belpomine, D., Dantchev, D., Du Rusquec, E. et al. T & B lymphocyte markers on the neoplastic cell of 20 patients with acute and 10 patients with chronic lymphoid-leukemia. Biomedicine, 1974; 20: 109.

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