Background

The higher incidence of acute lymphoblastic leukemia (ALL) among Hispanic children relative to that in other racial/ethnic groups is well-known. We evaluated incidence patterns of ALL in adults.

Methods

We analyzed the incidence patterns of ALL (ICD-03 codes 9835–9837) among all patients diagnosed from 1988–2004 in California using data from the California Cancer Registry to determine whether adult Hispanics also had higher incidence rates of ALL compared to non-Hispanic Whites (Whites). Age-adjusted incidence rates (AAIR), incidence rate ratios (IRR) and 5-year survival rates were obtained using SEER*Stat. AAIRs of other leukemia subtypes and IRRs relative to non-Hispanic whites were also examined as references of ALL.

Results

AAIRs of ALL in Hispanic males and females ages 20–54 years were higher compared to those in White males and females (IRR=1.99,95% CI=1.74–2.28 and IRR=1.91,95% CI=1.60–2.25 respectively). A higher AAIR of ALL was also observed among older (55+ years) Hispanic females (IRR=1.84, 95% CI=1.52–2.21), but not males (IRR= 1.07, 95% CI= 0.84–1.34). Among Hispanics, low socioeconomic status (SES) was associated with a higher AAIR compared to high/middle SES (IRR= 1.33, 95% CI=1.04–1.70). The respective five-year survival rates among ALL patients were 38% and 30% for Whites and Hispanics ages 20–54 years, and 8% and 12% for patients 55 years of age or older. Compared to other racial/ethnic groups, Hispanics did not have an increased IRR of the other major leukemia subtypes.

Conclusion

Hispanics experience a higher incidence of ALL throughout life, but not other subtypes.

Myeloid sarcomas are tumor masses composed of aggregates of malignant myeloid precursors in extramedullary sites including the skin. We report a case of myeloid sarcoma in a patient who presented with an ear lobe mass and facial nerve paralysis. Expression of CD56 by the malignant cells led to an initial misdiagnosis as Merkel cell tumor. Comprehensive pathological evaluation confirmed the diagnosis of myeloid sarcoma with aberrant expression of CD56 and carrying the translocation t(8;21) (q22;q22). Aberrant antigen expression by cutaneous myeloid sarcomas can cause diagnostic confusion with other cutaneous neoplasms. This is especially relevant when myeloid sarcoma is the sole manifestation of acute myeloid leukemia.

Although KIT mutations are present in 20–25% of cases of t(8;21)(q22;q22) acute myeloid leukemia (AML), concurrent development of systemic mastocytosis (SM) is exceedingly rare. We examined the clinicopathologic features of SM associated with t(8;21)(q22;q22) AML in ten patients (six from our institutions and four from published literature) with t(8;21) AML and SM. In the majority of these cases, a definitive diagnosis of SM was made after chemotherapy, when the mast cell infiltrates were prominent. Deletion 9q was an additional cytogenetic abnormality in four cases. Four of the ten patients failed to achieve remission after standard chemotherapy and seven of the ten patients have died of AML. In the two patients who achieved durable remission after allogeneic hematopoietic stem cell transplant, recipient-derived neoplastic bone marrow mast cells persisted despite leukemic remission. SM associated with t(8;21) AML carries a dismal prognosis; therefore, detection of concurrent SM at diagnosis of t(8;21) AML has important prognostic implications.