Necrotizing Sarcoid Granulomatosis (NSG): A Diagnostic Pitfall to Watch Out For!

Due to a 6 month history of recurrent bronchitis associated with shortness in breath a female patient in the mid-50s was referred for radiographic evaluation. The radiographic examination of chest showed rounded lesions at the level of the right central lobe and increased interstitial reticular opacity [Table/Fig-1]. The patient’s history and the radiographical findings described were suspicious for malignant disease. Thus, the patient was admitted and subjected to further work-up (tumour search). A CT scan of the lungs confirmed the presence of intrapulmonary rounded nodular opacities of up to 1.5 cm in diameter corresponding to the X-ray findings [Table/Fig-2]. For histocytopathological confirmation of the origin of the nodules, a bronchoscopy was initiated. Unfortunately, the bronchoscopy with brush biopsy yielded the unspecific finding of an alveolar hyperplasia accompanied by lymphocytic and granulocytic inflammatory reaction. Finally, the patient was submitted to diagnostic partial lung resection. The histopathological evaluation of the resected, paraffin-embedded tissue revealed an overlaying, nearly confluent nodular structure of strongly hyalinized tissue with anthracotic pigmentation and peripheral accumulation of epitheloid cell granulomas accompanied by infiltration of lymphoid cells. No PAS-positive micro-organisms were detectable [Table/Fig-3a&b].

[Table/Fig-1]:

Plain chest X-ray showing the presence of increased interstitial pronounced opacity (in PA and lateral view)

[Table/Fig-2]:

Axial CT scan of the chest showing several rounded opacities in various sizes (up to 1.5 cm in diameter)

[Table/Fig-3a,b]:

(a) Histopathological work-up (5x) of resected lung tissue showing sterile, nodular epitheloid cell granulomas, (b) increased fibro-hyalinized tissue with anthrotic pigmentation and peripheral accumulation of inflammatory cell infiltrates

Necrotizing sarcoid granulomatosis (NSG) is a rare condition related to the family of sarcoidosis [1]. In imaging it can be confused with a malignant aetiology. Thus, patients may be confronted with the suspicion of suffering from malignant disease. Based on imaging direct referral to oncology centers and even initiating therapy might be discussed before further differential diagnoses are considered. However, not all suspicious pulmonary nodules are malignant. The diagnosis still has to be made by histopathology of cellular material from broncho-alveolar lavage (cytological examination) or trans-bronchial biopsy. Unfortunately, in our case, these procedures did not yield a clear diagnosis. A diagnostic lung resection had to be performed.

The diagnosis was Necrotizing sarcoid granulomatosis of the lungs. The patient was accordingly treated with anti-inflammatory agents (non-steroidal antirheumatic drugs) and symptoms were regressive thereafter. NSG is a rare but generally benign disease that shares similarities with pulmonary vasculitis and classical sarcoidosis [2]. It can reveal as benign cause of seemingly deleterious situation. It should always be taken into consideration, as differential diagnosis for intrapulmonary or systemic disease, alone or in association with other entities [3].

[1]. Liebow AA, The J. Burns Amberson lecture: pulmonary angiitis and granulomatosis Am J Rev Respir Dis 1973 1089(108):1-17.  [Google Scholar]

[2]. Giraudo C, Nannini N, Balestro E, Meneghin A, Lunardi F, Polverosi R, Necrotizing sarcoid granulomatosis with an uncommon manifestation: clinicopathological features and review of literature Respir Care 2013, Dec 10 Respcare 02842 (ahead of print)  [Google Scholar]

[3]. Chowdhury FU, Sheerin F, Bradley KM, Gleeson FV, Sarcoid-like reaction to malignancy on whole-body integrated (18) F-FDG PET/CT Prevalance and disease pattern 2009 64(7):675-81.  [Google Scholar]