Radiological Characterization of Pulmonary Involvement in Patients With Hematological Diseases

Although infectious processes of the lungs are common in these immunosuppressed patient collectives, non-infectious causes account for up to half of the pulmonary manifestations found in hematologic malignancies. Besides the frequent infections including opportunistic pathogens, a broad differential diagnosis including drug-induced lung injury by cytostatic substances, cytokines, and innovative immunotherapeutic agents, rarer transfusion of blood products, and intrathoracic manifestations of the hematologic malignancy itself, must be kept in mind. Finally, vascular complications can also lead to pulmonary reactions. Early and consistent diagnostics and treatment of bronchopulmonary, intrathoracic, and vascular complications within the framework of hematologic systemic diseases can be essential for the patient's prognosis. Up to 25% of patients with profound neutropenia lasting for >10 days develop lung infiltrates, which frequently do not respond to broad-spectrum antibacterial therapy. While a causative pathogen remains undetected in most cases, Aspergillus spp., Pneumocystis jirovecii, multi-resistant Gram-negative pathogens, mycobacteria or respiratory viruses may be involved. In at-risk patients who have received trimethoprim-sulfamethoxazole (TMP/SMX) prophylaxis, filamentous fungal pathogens appear to be predominant, yet commonly not proven at the time of treatment initiation.

In patients who do not improve rapidly with first-line therapy with broad spectrum antibiotics, cross-sectional thoracic CT imaging is essential. It provides much better definition of the pattern of radiological changes that includes three main groups: consolidation, nodules (micro- and macro-), and diffuse changes, as ground glass pattern. Discuss these radiological patterns and how this guides the appropriate initial investigations and treatment options will be of a great value to be followed.