Diffuse alveolar hemorrhage

Classification of causes in immunocompetent patients

The etiology of pulmonary hemorrhage in individuals with normal immunity is extensive and traditionally divided into three major groups:

1. Immune-mediated conditions: primarily anti-basement membrane antibody disease (Goodpasture syndrome).
2. Conditions with presumed immune etiology:
3. Connective tissue disorders: rheumatoid arthritis, systemic lupus erythematosus (SLE), systemic sclerosis, and mixed connective tissue disease.
4. ANCA-associated vasculitides: granulomatosis with polyangiitis, Churg-Strauss syndrome, microscopic polyangiitis.
5. Other: antiphospholipid syndrome, cryoglobulinemia, Henoch-Schönlein purpura, and pauci-immune glomerulonephritis.
6. Conditions without a known immune link: idiopathic pulmonary hemosiderosis, valvular heart disease, disseminated intravascular coagulation (DIC), diffuse alveolar damage, and tumors. This group also includes drug reactions (cocaine, anticoagulants, trimellitic anhydride) and rapidly progressive glomerulonephritis without immune complex involvement.

Causes in immunocompromised patients

For immunocompromised individuals, the spectrum of probable causes of diffuse hemorrhage narrows significantly. This group includes only three main categories of pathologies:

• Infectious processes.
• Malignancies.
• Blood dyscrasias (Blood dyscrasias).

Goodpasture Syndrome

Anti-basement membrane antibody disease has a distinct epidemiological profile: the disease typically affects young males (the sex ratio is approximately 3:1 in favor of males).

The pathogenesis is based on systemic glomerulonephritis. Specific antibodies directed against basement membrane components in lung and kidney tissues circulate in the blood serum. Clinically, pulmonary manifestations (including hemorrhage) often dominate and present first, but concurrent kidney disease is detected in the majority of patients upon detailed examination.

Granulomatosis with polyangiitis (Wegener's)

Granulomatosis with polyangiitis (GPA) is a primary idiopathic small-vessel vasculitis accompanied by necrotizing granulomatous inflammation of the respiratory tract. It can occur at any age (from early childhood to 70+ years) with equal frequency in both sexes. The etiology is unclear, but there is a clear association with c-ANCA (proteinase-3 anti-neutrophil cytoplasmic antibodies).

Clinically, the disease manifests with symptoms from the nose, sinuses, or chest (cough, dyspnea, pleuritic chest pain, hemoptysis). If the process does not extend beyond the respiratory tract, it is referred to as "limited" GPA.

Radiological findings (CT and X-ray):

• Nodules and masses: detected in 70–90% of patients. Ranging from a few millimeters to 10 cm in size, they are distributed bilaterally without a strict zonal preference, tending to be multiple and growing.
• Cavitation: breakdown with cavity formation frequently occurs in nodules greater than 2 cm in size. This is a classic, but not mandatory, sign.
• CT-specific signs: ground-glass halo sign (a sign of peripheral hemorrhage), feeding vessel sign, linear strands and spicules extending to the pleura (pleural tags).
• Airways: stenoses of large airways (subglottic region, trachea, bronchi), bronchiectasis in 40% of cases.
• Rare signs: atelectasis, pleural effusion, and lymphadenopathy.

With adequate treatment, the nodules regress, but the radiological picture may lag behind the clinical course by a month, and parenchymal scarring often persists on CT.

Organizing pneumonia (OP)

Organizing pneumonia is not an independent infection, but a specific histological pattern of lung tissue response to injury, first described in 1983. If the cause of the injury is unclear, the disease is termed cryptogenic organizing pneumonia (COP).

Important: the term "bronchiolitis obliterans organizing pneumonia" (BOOP) was previously widely used. Today it is considered obsolete, as the changes in the bronchioles are secondary, and true "bronchiolitis obliterans" is absent.

The disease begins insidiously (insidious onset). Patients are troubled by cough, night sweats, fatigue, and weight loss. Biopsy reveals plugs of fibrous tissue (bourgeons conjunctifs) in the alveolar ducts. CT reveals bilateral areas of consolidation (patchy) that typically gravitate toward the peripheral lung regions. A key clinical feature of the condition is a phenomenally rapid and pronounced response to corticosteroid therapy.

Class and exam questions

What else to study on this topic

• ANCA-associated vasculitides: differential diagnosis of microscopic polyangiitis and Churg-Strauss syndrome.
• Idiopathic pulmonary hemosiderosis: clinical presentation and prognosis.
• Drug-induced hemorrhages: the impact of cocaine and trimellitic anhydride on alveolar tissue.
• Diffuse alveolar damage as an outcome of various pathological processes in the lungs.

Other topics in the «Chest Radiology» section

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