Necrotising sarcoid granulomatosis (NSG) was first described by Liebow1 in 1973. It is defined by three pathological features: the presence of a conglomerate mass of sarcoid-like granulomas; varying degrees of necrosis within the confluent granulomas; and vasculitis with granulomas and giant cells involving the walls of muscular arteries and veins. The relationship between NSG and classic sarcoidosis is controversial. In NSG hilar lymphadenopathy is not seen as frequently as in sarcoidosis, extrapulmonary involvement is rare and serum levels of angiotensin-converting enzyme (ACE) are not necessarily raised.2

The cause of sarcoidosis is unknown, but it has been hypothesised that it results from exposure of a genetically susceptible individual to specific environmental agents. Abe et al3 isolated Propionibacterium acnes (P acnes) in culture from sarcoidosis biopsy specimens, and recently the P acnes genome has been detected in sarcoid lymph nodes by polymerase chain reaction4 and in situ hybridisation.5 The P acnes genome was less frequently and less abundantly detected in tuberculosis specimens.4 5 Thus, an aetiological relationship between P acnes and sarcoidosis has been advocated. We report here the first case of a patient with NSG in whose lung specimens were found abundant P acnes genome.

A 65-year-old female non-smoker with no history of dust exposure or pet ownership was referred to our hospital with bloody sputum. The patient’s superficial lymph nodes were not palpable. No abnormal findings were revealed by ophthalmological or otolaryngological examinations. Serum levels of C-reactive protein and lysozyme were raised to 2.62 mg/dl and 10.8 μg/ml, respectively. Antinuclear antibody, rheumatoid factor and antineutrophil cytoplasmic antibody were negative. The ACE level was within the normal range. A skin test with purified protein derivative was negative. Small mediastinal and hilar lymph nodes were detected on CT scanning. Multiple irregularly marginated consolidations with air bronchograms were distributed predominantly in peribronchovascular or subpleural lesions of both lungs on a high-resolution CT scan. Total cell count of bronchoalveolar lavage fluid was 9.7×105/ml with a cell population of 88% macrophages, 5% neutrophils, 5% lymphocytes and 2% eosinophils; the CD4+/CD8+ ratio was 11.1. Pathological findings of open lung biopsy specimens were consistent with NSG (fig 1A and B) and no pathogenic organisms (including mycobacteria and fungi) were detected in culture of the biopsy specimens. The patient was diagnosed with NSG. P acnes DNA was detected in abundant amounts in the granulomas by in situ hybridisation (fig 1C).5

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Figure 1 (A) Open lung biopsy specimen revealing necrotising granulomas (arrow) with giant cells aggregated in masses and distributed in a lymphangitic pattern. (B) Granulomatous vasculitis was also present: granulomas infiltrated the vascular walls and almost completely occluded the lumens of the vessels. (C) Genomic DNA of Propionibacterium acnes was detected in abundant amounts by in situ hybridisation in the lung tissue of a patient with necrotising sarcoid granulomatosis. Numerous dots indicate the existence of P acnes in the granulomas.

This is the first report of NSG with P acnes DNA found in the granulomas of lung specimens. This may indicate an aetiological link between NSG and P acnes, and it also suggests that NSG is an atypical sarcoidosis with a common aetiology. The clinical and pathological differences between these diseases could be explained by variability in the host response to P acnes or the histological location of P acnes, although further study would be necessary to arrive at more definite conclusions.

Acknowledgements

We thank Dr Tamiko Takemura (Japanese Red Cross Medical Center) and Dr Yoshinori Kawabata (Saitama Cardiovascular and Respiratory Center) for pathological discussion.