Granular acute lymphoblastic leukemia in adults: report of a case and review of the literature.

Abstract: The diagnosis of granular acute lymphoblastic leukemia (ALL) can be problematic as the cytoplasmic granules found in many blast cells may mimic those seen in acute myelogenous leukemia (AML). This rare variant of B-cell ALL is more commonly diagnosed in children, but may occur in adults. We report a case of granular B-ALL in a 56-year-old female and review the literature.

Key Words: leukemia, lymphoblast, granular acute lymphoblastic leukemia

Case Report

A 56-year-old Caucasian female presented with a two-month history of weight loss, fatigue, weakness, pallor and right-sided chest pain. Physical examination revealed significant splenomegaly.

Review of the peripheral blood showed 16% blasts with large, variably irregular nuclei, prominent nucleoli and moderate to abundant cytoplasm. Approximately 10% of these blasts contained numerous azurophilic cytoplasmic granules (Fig). The patient was admitted to the Hematology/Oncology service and a bone marrow aspirate and biopsy were performed.

Review of the bone marrow aspirate and biopsy revealed a predominance of blasts. These cells had large, variably irregular nuclei with multiple nucleoli and abundant cytoplasm, and 15% of the blasts demonstrated numerous cytoplasmic granules, but no Auer rods. These blasts were positive for periodic acid-Schiff (PAS) staining, and for [alpha]-naphthyl butyrate esterase (B-EST), [alpha]-naphthyl acetate es-terase (A-EST) without inhibition by fluoride, CD79a and terminal deoxynucleotidyl transferase (TdT). They were negative for myeloperoxidase (MPO), for chloroacetate esterase (CAE) and for all other myeloid and T-cell markers.

Cytogenetic analysis revealed 46, XX, t(9; 22) (q34; q11.2) [3]/47, idem, +der(22 t(9;22)(16)/48, idem, +21. (1) FISH analysis confirmed the presence of a double Philadelphia chromosome. Flow cytometric analysis demonstrated a large population of CD45 dim mononuclear cells expressing CD10, CD19, CD34, HLA-DR, TdT, but negative for CD20, surface immunoglobulin, as well as myeloid, monocytic and T-lymphocytic markers. Diagnostically significant negative markers in this case were MPO, CAE, Lowder, lysozyme, CD20 and CD68. A diagnosis of granular ALL was rendered after evaluation by the EGIL (European Group on Immunologic Classification of Leukemias) biphenotypic system showed the patient to score less than 2 points in the myeloid and T-cell groupings, which mitigates against biphenotypic lineage.

The patient is currently more than 7 months post diagnosis and has undergone hyper-CVAD chemotherapy through cycle 4A, with six cycles each of intrathecal methotrexate and ara-C. The patient's most recent bone marrow biopsy showed no evidence of residual leukemia and the patient was referred to another hospital for matched unrelated bone marrow transplantation.

Discussion

Granular ALL accounts for 2 to 8% of all ALL cases in children but is very rare in adults. An extensive search of the world literature revealed 9 unequivocal cases of granular B-lineage-ALL in adults and no definite cases of granular T-lineage-ALL (Table). Several older reports were called "null" or "non-B-non-T-cell" type. (1,2) As these cases were not well-characterized by immunophenotypic and molecular means, they have not been included in the present discussion. Aside from the prominent intracytoplasmic granules, these cases are indistinguishable, both clinically and phenotypically, from more conventional cases of ALL at presentation.

In addition, there exists significant variability in the presentation of granular ALL (see Table). This variability can be the most misleading aspect concerning the differentiation between granular ALL and other entities. Although immunophenotyping of all adult acute leukemia cases has greatly simplified the diagnosis of granular ALL, this disease process remains a potential area of difficulty. Given the highly variable presentation of granular ALL, significant and highly variable discrepancies in morphology and immunophenotype can exist. The purpose of this literature review is to recognize the variability of this rare disease process and to alleviate physician concern regarding this discrepancy. While the tools for correct interpretation are readily available and commonly used, diagnosis in adults requires a high index of suspicion. (3)

[FIGURE OMITTED]

Patients with granular ALL typically present with sheets of large blasts containing moderate to abundant cytoplasm, with greater than 5% of the blasts demonstrating clearly visible azurophilic cytoplasmic granules. Rare cases have granules within the majority of lymphoblasts. The morphologic features may complicate the diagnostic workup, as the blasts closely resemble myeloblasts (Fig).

Cytochemical features of this process may include positivity for PAS, acid phosphatase, B-EST, and A-EST uninhibited by fluoride. Negative staining for MPO and CAE is typical.

The immunophenotypic profile of the blasts is most commonly that of precursor-B cells, without evidence of myeloid or monocytic derivation. If positivity for any myeloid marker is identified, a diagnosis of bilineage or biphenotypic leukemia must be entertained and the leukemic cells must be scored for lineage. The current EGIL scoring system was used in this case; the case did not meet criteria for a bilineage leukemia, having a score of only 0.5 in both myeloid and T-lineage groups (7) Bilineage leukemia is an additional potential cause of disparities between immunophenotype and morphology and should always be considered and scored in these cases.

Two adult cases of granular T-lineage ALL have been reported, but on critical analysis they did not appear to truly be of T-cell lineage. One demonstrated a TCR gene rearrangement but a B-lymphoblast immunophenotype. (6) This previously described case probably represents a rare instance of B-lineage ALL with a coincidental TCR gene rearrangement. (8) The second case appears to be either T-lineage large granular lymphocytic (LGL) leukemia or an aggressive NK-cell leukemia. There was no mediastinal mass, and the blasts reportedly were CD2, CD3, and CD7 positive, but there was no mention of CD4, CD8, CD56 or TdT positivity. (9)

Ultrastructurally, the cytoplasmic granules appear to be either mitochondria or lysosomes, with several cases showing electron dense tubular structures, 900 nm doughnut-shaped particles and inclusions resembling lysosomes. (10,11) The granules of granular ALL initially may resemble those of Chediak-Higashi disease, but the clinical presentation and EM studies usually will highlight clear differences. (5)

Cytogenetic studies add valuable information to the diagnostic evaluation of ALL as 15 to 30% of all adult ALL cases have a Philadelphia (Ph) chromosome compared with only about 5% of pediatric cases. The Ph is a known indicator of poor prognosis in ALL, with a complete remission (CR) rate of less than 5% in adults with the t(9;22) translocation contrasted with a CR rate of approximately 30% in those without it. (12) This case is the only reported adult or pediatric granular ALL with a double Ph. Previous reports show occasional cases of a t(9;22) translocation to yield a single Ph in both adults and children with granular ALL. (4,11)

In view of Philadelphia chromosome positivity and the patient's age, it might be suspected that the patient had CML presenting in blast crisis. However, FISH analysis of the blast population showed bcr/abl fusion at the major breakpoint and a second clone with a minor breakpoint fusion. Additional clones included a third clone with a minor breakpoint fusion and an additional copy of the Philadelphia chromosome and a fourth clone with a minor breakpoint and three additional copies of the Ph chromosome. While it does not totally exclude CML, this degree of variability in the breakpoint region would be highly unlikely in a case of CML. Additional FISH studies looking for the Ph chromosome in normal granulocytes would be useful in excluding CML. In this case, given the low blast counts and absence of granulocytosis or basophilia, the possibility of CML was unlikely and this FISH study was not performed.

Pediatric patients with granular ALL have a worse prognosis than those with nongranular varieties. (10) As noted, adult cases of granular ALL are exceedingly uncommon but seem to carry a poor prognosis also. Five of the nine adult patients failed to go into remission and they had a mean survival of only 7.5 months after diagnosis. (3'4) The four adult patients who achieved an initial CR have had a mean survival of at least 12 months and several are still alive. (3,5,6) Statistical significance is not reached, however, because of the rarity of this diagnosis in adults.

Conclusion

This patient presented with pancytopenia and circulating blasts, a pattern characteristic of acute leukemia. On the basis of cellular morphology alone, it would have been extremely difficult or impossible to make the diagnosis of granular ALL. However, the classic immunophenotypic profile of precursor-B ALL led to the correct interpretation. In this case, an accurate diagnosis was obtained expeditiously by the combination of morphologic findings, flow cytometry and cytochemical/immunohistochemical staining. This case highlights the great importance of a systematic, multiparametric approach to a diagnosis of bone marrow pathology in all cases of suspected acute leukemia. Proper therapy depends on an accurate diagnosis and an accurate diagnosis depends on maintaining a high index of suspicion and using all appropriate diagnostic modalities.

References

1. Rosen NR, DiFino S, Nelson DA, et al. Acute leukaemia with unusual cytoplasmic inclusions. Cancer 1979;43:2405-2409.

2. Yanagihara ET, Naeim F, Gale RP, et al. Acute lymphoblastic leukemia with giant intracytoplasmic inclusions. Am J Clin Pathol 1980;74:345-349.

3. Canta-Rajnoldi A, Inverizzi R, Biondi A, et al. Biological and clinical features of acute lymphoblastic leukemia with cytoplasmic granules or inclusions: description of eight cases. Br J Haematol 1989; 73:309-314.

4. Hay CR, Barnett D, James V, et al. Granular common acute lymphoblastic leukaemia in adults: a morphological study. Eur J Haematol 1987;39:299-305.

5. Fradera J, Velez-Garcia E, White JG. Acute lymphoblastic leukemia with unusual cytoplasmic granulation: a morphologic, cytochemical, and ultrastructural study. Blood 1986;68:406-411.

6. Schwarzinger I, Fodinger M, Scherrer R, et al. Hypergranular acute lymphoblastic leukemia (ALL): report of a case and review of the literature. Ann Hematol 1993;67:301-303.

7. Brunning RD, Matutes E, Borowitz M. Acute leukaemias of ambiguous lineage. In: Jaffe ES, Harris NL, Stein H, eds. Tumours of Haematopoietic and Lymphoid Tissues. Lyon, France, IARC Press, 2001, p 106.

8. van der Velden VH, Szczepanski T, Wijkhuijs JM, et al. Age-related patterns of immunoglobulin and T-cell receptor gene rearrangements in precursor B-ALL: implications for detection of minimal residual disease. Leukaemia 2003;17:1834-1844.

9. Tsoi WC, Lai HD, Feng CS. T-acute lymphoblastic leukemia with cytoplasmic granules. Am J Hematol 1997;56:193-194.

10. Cerezo L, Shuster JJ, Pullen DJ, et al. Laboratory correlates and prognostic significance of granular acute lymphoblastic leukemia in children: a Pediatric Oncology Group study. Am J Clin Pathol 1991;95:526-531.

11. Stein P, Peiper S, Butler D, et al. Granular acute lymphoblastic leukemia. Am J Clin Pathol 1983;79:426-430.

12. Faderl S, Jeha S, Kantarjian HM. The biology and therapy of adult acute lymphoblastic leukemia. Cancer 2003;98:1337-1354.

What counts is not necessarily the size of the dog in the fight--it's
the size of the fight in the dog.
--Dwight D. Eisenhower

James W. Fulcher, MD, Thomas J. Allred, MD, Anita Kulharya, PhD, K.L. Satya-Prakash, phD, Maree Seigler, HT, Doris Neibarger, MT, and Fermina M. Mazzella, MD

From the Department of Pathology and Laboratory Medicine, Medical College of Georgia, August, GA.

Reprint requests to James W. Fulcher, Department of Pathology and Laboratory Medicine, Medical College of Georgia, BI-2026A, 1120 15th Street, August, GA 30912. Email: [e-mail]

Accepted April 6, 2006.

RELATED ARTICLE: Key Points

* Granular lymphoblastic leukemia is most commonly seen in children, but the diagnosis should be considered in adults as well.

* Cases of granular lymphoblastic leukemia in adults may look morphologically similar to acute myelogenous leukemia; thus, morphology alone may lead to misdiagnosis in these patients.

* There is great variation in patient age, in presentation blast count and in blast morphology in the reported cases, which highlights the importance of histochemical and immunophenotypic studies in these cases.

* We report the first double Philadelphia chromosome found in an adult with granular acute lymphoblastic leukemia (ALL). Philadelphia chromosome is an indicator of poor prognosis in childhood ALL, but its significance in granular adult ALL is as yet unknown.

Table. Pertinent data of 9 known cases of adult granular acute
lymphoblastic leukemia (ALL)

                                                                %Gr
Patient  Age  Gender  Hgb   WBC    ANC    Plt    Liver  Spleen  Blasts

1*       56   F        4.1    2.9    783   26    N      Y       15
2        22   M        8.5   31.2      -   99    -      -       25
3        58   M        8.2    1.7      -    2.3  -      -       47
4        38   M        6.3    2.2      -   44    -      -       41
5        21   F        9.8   80.0      -  243    -      -       30
6        20   M        6.5   12.6      -   68    Y      Y       30
7        54   F        7.1    0.4      -   60    Y      Y       25
8        45   F       14.7  158    11060  264    Y      N       35
9        38   M        8.6   18.7   3927  113    N      N       45

                             Survival
Patient  Age  Karyotype  CR  (mo)

1*       56   Double Ph  ?    >7
2        22   -          Y   >27
3        58   -          N     8
4        38   -          N    14
5        21   -          N     7
6        20   -          N     7
7        54   Ph         N     1
8        45   -          Y    >5
9        38   Normal     Y    >8

Case 1 is the present case and the patient is still alive; cases
2-5 (3), cases 6-7 (4), case 8 (5), case 9 (6).
Hgb, hemoglobin; WBC, white blood count; ANC, absolute neutrophil count;
Plt, platelets; Gr, granular; CR, complete; response; Ph, Philadelphia
chromosome.