Lung: Nonneoplastic Diffuse Disease: Diagnosis

Tissue procured to diagnose nonneoplastic lung disease is generally taken as a wedge-shaped fragment from the periphery of 1 or multiple lobes. Staples in the margin, if present, must be removed.

The wedge biopsy is serially sectioned in parallel to the long axis of the specimen and examined for any focal lesions. A representative section may be submitted for frozen section evaluation.

SURGICAL/CLINICAL CONSIDERATIONS

Goal of Consultation

Provide preliminary diagnosis for patients with diffuse lung disease and aid in allocation of tissue for special studies

Change in Patient Management

Preliminary diagnosis can help guide immediate management (inflammatory vs. infection vs. neoplasm)

Clinical Setting

Majority of patients are critically ill; clinical differential diagnosis includes a variety of neoplastic, infectious, or inflammatory causes

SPECIMEN EVALUATION

Gross

Specimen is serially sectioned and examined thoroughly to exclude any focal or mass lesions
Specimen is kept sterile in case tissue needs to be taken for cultures or other special studies (1 cm³ is minimal amount of tissue for testing)

Frozen Section

Representative section of tissue is frozen

MOST COMMON DIAGNOSES

Bronchopneumonia/Abscess

Tissue may need to be taken for culture if not already done so clinically

Granulomatous Inflammation

Necrotizing granulomas favor infection, and diagnostic findings (e.g., fungal yeast or hyphae) should be mentioned, if present
Numerous confluent, well-formed, nonnecrotizing granulomas in lymphangitic distribution suggest sarcoidosis
Rare, poorly formed interstitial granulomas or histiocyte aggregates may suggest hypersensitivity pneumonitis
Confluent (geographic) zones of necrosis with scattered multinucleated giant cells and without wellformed granulomas may suggest granulomatosis with polyangiitis (previously Wegener granulomatosis)

Viral Infection

Must demonstrate viral inclusions, often in a background of necrotizing pneumonitis or diffuse alveolar damage
- Prominent nucleoli in reactive pneumocytes can mimic inclusions but lack a peripheral halo

Interstitial Lung Disease

If interstitial lung disease is suspected on frozen section, final diagnosis should be deferred to permanent sections for thorough sampling

REPORTING

Frozen Section

Description of histologic findings is generally sufficient (e.g., nonnecrotizing granulomatous inflammation, patchy interstitial fibrosis)
Absence of neoplasm should be noted
Most nonneoplastic entities will require evaluation of permanent sections, thus a final diagnosis is often deferred

PITFALLS

Failure to Identify a Malignant Process

Dense inflammatory infiltrates can obscure malignant cells

RELATED REFERENCES

1. Sienko A et al: Frozen section of lung specimens. Arch Pathol Lab Med. 129(12):1602-9, 2005

Image Gallery

(Left) Acute bronchopneumonia is characterized by predominantly acute inflammatory cells (neutrophils) within the alveolar spaces &/or lumina of bronchioles. This finding can be diffuse, patchy, or somewhat focal. The infiltrate may also be associated with food particles in cases of aspiration pneumonia. (Right) The neutrophilic infiltrate may be associated with bacterial clusters, fungal elements, or food material, depending on the etiology. Tissue should always be sent for microbiologic culture.

(Left) A diagnostic finding in certain viral infections is the presence of nuclear &/or cytoplasmic inclusions. These inclusions

vary in size, but most have a dark-staining quality that allows for identification even at lower magnifications. The background lung may show necrosis, pneumonitis, or diffuse alveolar damage. (Right) This image shows 2 nuclear “owl’s-eye” inclusions