Hard-Metal Disease

Tan-Lucien H. Mohammed, MD, FCCP

Key Facts

Terminology

Hard-metal disease: Pneumoconiosis due to dust inhalation of cemented tungsten carbide (WC)
- Distinct histologic finding of giant cell pneumonitis

Imaging Findings

Ground-glass opacities > reticular opacities
Often panlobular
Large peripheral cystic spaces (not honeycombing): Either cysts or lobular hyperplasia

Top Differential Diagnoses

Pathology

Hallmark of GIP is multinucleated giant cells, which show cannibalism
Cobalt highly soluble, rarely detected in tissue; tungsten remains and serves as marker of exposure
Disease dependent on sensitization to cobalt, not dust burden
At risk: Workers who manufacture high speed WC saws, drill bits, or sharpening discs

Clinical Issues

Axial HRCT shows nonspecific diffuse ground-glass opacities

. The patient’s occupational history of metal grinding suggests hard-metal disease.

Axial HRCT shows perihilar progressive massive fibrosis

and peripheral lobular hyperinflation

in this patient with a long history of cobalt exposure. Hard-metal disease was the diagnosis.

TERMINOLOGY

Abbreviations and Synonyms

Hard-metal disease (HMD), tungsten carbide pneumoconiosis, hard-metal lung, giant cell interstitial pneumonitis (GIP), cobalt lung

Definitions

Hard-metal disease: Pneumoconiosis due to dust inhalation of cemented tungsten carbide (WC)
- Distinct histologic finding of giant cell pneumonitis

IMAGING FINDINGS

General Features

Best diagnostic clue: Radiographic findings of interstitial lung disease in patient with history of exposure to WC
Patient position/location: Ground-glass opacities commonly panlobular or multilobular
Morphology: Nonspecific ground-glass opacities with irregular reticular opacities most common

CT Findings

Few reported cases to draw conclusions
Nonspecific findings, morphology varies widely from ground-glass opacities to end-stage fibrosis
Morphology
- Ground-glass opacities > reticular opacities
  - Often panlobular
- Craniocaudad distribution
  - Lower lung zones or random
  - Fibrosis: Unclear distribution, like other dusts such as silicosis, may result in progressive massive fibrosis (PMF) in upper lung zones
- Axial distribution
  - Random > subpleural
- Centrilobular nodules, often subpleural
- Large peripheral cystic spaces (not honeycombing): Either cysts or lobular hyperplasia
No reports that WC increases density of abnormal lung or lymph nodes
Other
- Adenopathy (< 2 cm short axis diameter), frequency unknown
- Pleural disease: Absent
Radiology-pathology correlation
- Ground-glass opacities: Alveolar filing with macrophages and multinuclear giant cells (MGCs)
- Centrilobular nodules: Bronchiolocentric fibrosis