Caplan's Syndrome with a twist

Our plain-English summary of Caplan's Syndrome with a twist, by J. Deepak, B. Kenaa (International Journal of Clinical Case Reports and Reviews, 2020).

The study

• Authors: J. Deepak, B. Kenaa
• Journal: International Journal of Clinical Case Reports and Reviews
• Published: 2020;2(1)
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Unlabelled: Caplan's syndrome is seen in patients with rheumatoid arthritis (RA) and chronic silica inhalation. We present a patient with RA who presented with multiple pulmonary nodules. Biopsy of the nodules revealed silica crystals under polarized light. He continued treatment for RA and his pulmonary nodules remained stable. However, he subsequently developed renal failure with nephrotic range proteinuria. We discuss silica and the associated autoimmunity in patients with chronic occupational exposure.

Background: Caplan's syndrome also known as rheumatoid pneumoconiosis is a disease entity that is seen in patients with rheumatoid arthritis (RA) exposed to chronic silica and inorganic dust [1,2]. Classically, they form peripheral well-defined pulmonary nodules with characteristic silica retained in the necrobiotic center. In addition, epidemiological data has shown some association with silica and autoimmunity [3]. We present a case of silica and asbestosis exposure in a patient with rheumatoid arthritis who developed rheumatoid pneumoconiosis and subsequent renal failure. We highlight this rare disease, progression as well as other associated complications.

In plain English

This was a case report about one patient: a 73-year-old man with rheumatoid arthritis (RA) and no smoking history, referred for multiple growing lung nodules. He was a Navy veteran exposed to asbestos in the Navy. He later oversaw production of plastic and metal parts for 10 years, worked in residential construction, and spent about 5 years stripping paint from brick on old houses. A biopsy of the nodules showed necrotic tissue with silica crystals under polarized light, consistent with silico-anthracotic nodules, and was negative for cancer. Lung washing (bronchoalveolar lavage) showed no infection, and cultures for acid-fast bacteria and fungi were negative. Breathing tests showed a mild obstructive defect. Three years later he developed worsening kidney failure. A kidney biopsy showed a mix of minimal change disease and focal segmental glomerulosclerosis, with no silica deposits. His lung nodules did not worsen. The authors wrote that it is unclear what role silica exposure played in the kidney disease. They concluded that Caplan's syndrome (rheumatoid pneumoconiosis) remains rare and that the causal link between silica, RA and autoimmunity remains unclear.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report (single patient)
• Who was studied: One 73-year-old man with rheumatoid arthritis and no smoking history, a Navy veteran, referred to a pulmonary clinic (authors at the Baltimore VA Medical Health Center) for multiple pulmonary nodules
• Exposure: Asbestos exposure in the Navy (fiber type not stated). Afterwards he spent 10 years overseeing production of plastic and metal parts for guided radar systems, then worked in residential construction (hanging, siding, replacing windows), and spent about 5 years restoring brick on old houses by stripping off paint. Silica was found in the lung nodules; the article does not say which job it came from.
• Main results:
  • Transbronchial biopsy of the right upper lobe nodules showed necrotic tissue with central silica crystals under polarized light, consistent with silico-anthracotic nodules. The biopsies were negative for cancer.
  • Separately from the biopsy, bronchoalveolar lavage showed no evidence of infection, and AFB and fungal cultures were negative.
  • Pulmonary function testing showed a mild obstructive ventilatory defect: FEV1/FVC 66%, FEV1 3.13 L (94% predicted).
  • Three years after the lung biopsy he had worsening renal failure. Renal biopsy showed a mixture of minimal change disease and focal segmental glomerulosclerosis. Staining was negative for amyloid and no silica deposits were found.
  • Right heart catheterization showed mild pulmonary hypertension (mean pulmonary artery pressure of 33). Chest CT did not show worsening of the nodules, and his lung status stayed the same over 3 years.
• The authors' conclusion: The authors concluded that Caplan's syndrome remains a rare disease and that the exact causal relationship between silica, RA and autoimmunity remains unclear. They also wrote that diagnosis requires a thorough occupational history and sampling of the nodule.
• Limitations the authors state:
  • The authors stated it is unclear what role silica exposure played in the patient's kidney disease, since the kidney biopsy showed no immune deposits or silica crystals.

Topics

Medical terms in this study, explained in our Lexicon: Biopsy, Occupational Exposure, Pneumoconiosis.

Related studies

• Rheumatoid pneumoconiosis (Caplan's syndrome) in an asbestos worker — W.G. Tellesson (1961)
• Rheumatoid "pneumoconiosis" (Caplan's syndrome) in an asbestos worker: a 17 years' follow-up — I.A. Greaves (1979)
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