Two autopsy cases of pulmonary leukemic infiltration mimicking severe pneumonia in patients with acute myeloid leukemia

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Diverse pulmonary complications are often observed in acute myeloid leukemia.

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Clinically significant leukemic infiltration is rarely recognized antemortem.

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Autopsy revealed leukemic infiltration in patient mimicking severe pneumonia.

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It may be difficult to achieved accurate diagnosis without pathological examination.

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Non-invasive examinations for leukemic infiltration diagnosis are required.

Although a previous autopsy series demonstrated that pulmonary leukemic infiltration (PLI) is a major pulmonary complication in patients with acute myeloid leukemia (AML), an antemortem diagnosis of PLI is rare. Diverse pulmonary complications cause acute respiratory failure (ARF) in patients with AML undergoing chemotherapy. This article reports two elderly patients with AML who presented with ARF due to PLI mimicking severe pneumonia during induction chemotherapy. Accurate antemortem diagnosis of PLI was almost impossible without pathological examination since the clinical course was not typical of PLI. We recommend considering PLI in patients with AML who have an unknown etiology of ARF.

CT classification of acute myeloid leukemia with pulmonary infiltration

PURPOSE

To characterize and categorize the CT findings of pulmonary leukemic infiltration (PLI) in patients with acute myeloid leukemia (AML).

MATERIALS AND METHODS

Among 435 patients with AML, 20 patients with PLI were retrospectively selected, and clinical characteristics and CT findings were analyzed. PLI was categorized into four patterns according to CT findings: type A, multiple nodules and/or masses; type B, bilateral perihilar airspace opacities (GGA or consolidation) without any nodules or masses; type C, mixture of type A and B; and type D, PLI without visible abnormal lung opacity. The difference in overall survival among four CT patterns was also examined.

RESULTS

The frequency of complex karyotypes was higher in AML patients with PLI than in whole AML patients. Percentages of patients with CT findings of type A, B, C, and D were 35%, 20%, 35%, and 10%, respectively. There was a clear difference in the localization of opacities according to the type of infiltrates, i.e., nodules/masses were mainly detected in the lower/peripheral portion. Conversely, GGA was mainly located in the upper/central portion. The median overall survival from diagnosis of PLI was 262 days (range 12-1148). The CT pattern was not significantly associated with survival (p = 0.3), with the exception of patients with type C tending to have significantly better outcomes compared to patients with type B (p = 0.05).

CONCLUSION

This classification can contribute in accurate non-invasive diagnosis and possibly in the estimation of prognosis.

[Leukemic pulmonary infiltration diagnosed by sputum Giemsa-staining]

A 54-year-old man with acute myeloid leukemia (AML) underwent allogeneic bone marrow transplantation from a human leukocyte antigen-matched unrelated donor in nonremission status. Bone marrow aspiration performed on day 14 showed that the patient had achieved complete remission; however, he relapsed on day 28. The patient developed a wet cough, and chest computed tomography performed on day 27 revealed pneumonia. Because pneumonia developed along with the leukemic relapse, we suspected that it was due to pulmonary leukemic infiltration (PLI). Giemsa-stained sputum showed some blast cells and fluorescence in situ hybridization indicated that the patient had monosomy 7, which was also detected in bone marrow blasts. Though we prescribed hydroxycarbamide and decreased tacrolimus rapidly, AML progressed and led to the patient's death on day 45. Histopathological findings of the autopsy performed the next day showed diffuse alveolar damage in both lungs. The blast cells were packed in blood vessels of alveolar septa and were also seen in alveoli. PLI was diagnosed pathologically. In conclusion, our case demonstrates that Giemsa stain of sputum is useful in quick diagnosis of PLI without invasive examination.

[Pulmonary infiltration of acute monoblastic leukemia diagnosed by transbronchial lung biopsy]

A 65-year-old woman was urgently admitted to our hospital for antibiotic-resistant fever, hypoxemia, and hyperleukocytosis and was diagnosed with acute monoblastic leukemia. Chest computed tomography revealed interlobular septal thickening, central ground-glass opacity, and a nodular shadow in the left lower lobe. Although several treatments for infectious disease and acute heart failure were administered, they were less effective. Transbronchial lung biopsy was performed on day 7 of hospitalization, and subsequently, pulmonary leukemic infiltration was confirmed. Based on the diagnosis, we decided to start intensive chemotherapy. Consequently, the abnormal lung shadow on computed tomography vanished, and complete hematological remission was achieved. Although acute myeloid leukemia is frequently associated with lung infiltration during onset, it is often difficult to distinguish it from other pulmonary complications. In clinical practice, intensive chemotherapy is often initiated based on the clinical evaluation without pathological confirmation of the lung disease. Our patient was accurately diagnosed based on the pulmonary leukemic infiltration observed pathologically and recovered well. Here we report our case along with a discussion of the relevant literature.