|Year : 2007 | Volume
| Issue : 3 | Page : 100-101
All that caseate is not T.B.
V Karkhanis, JM Joshi
Department of Respiratory Medicine, T. N. Medical College and B. Y. L. Nair Hospital, Mumbai., India
J M Joshi
Department of Respiratory Medicine, T. N. Medical College and B. Y. L. Nair Hospital, Mumbai-400008.
Source of Support: None, Conflict of Interest: None
| Abstract|| |
We report a case of parotid swelling, provisionally diagnosed as tuberculous inflammation in view of granuloma showing caseous necrosis on cytology and started on antituberculosis drugs. However, on detailed clinical examination and investigations diagnosis of sarcoidosis was made. She responded well to treatment with steroids. The correlation of caseation necrosis and sarcoidosis has been described.
Keywords: Sarcoidosis, Caseation
|How to cite this article:|
Karkhanis V, Joshi J M. All that caseate is not T.B. Lung India 2007;24:100-1
| Introduction|| |
Although non-caseating granulomas are usual findings in sarcoidosis, necrosis does occur. Caseating granulomas are characteristic of Mycobacterium tuberculosis fection but are not pathognomic of the same. Granulomata in sarcoidosis consist of focal collection of macrophages, a few multinucleated giants cells and lymphocytes. Langhan's giant cells and foreign body type giant cells are identified around Schumann's bodies. Fibrinoid necrosis is spotty and relatively inconspicuous; it may be present at the centers of the granulomata, proceeding to either complete resolution or conversion into hyalinized fibrous tissue. 
| Case|| |
A 48 years old female, presented with right facial palsy, bilateral parotid swelling, predominantly dry cough and dyspnoea of one-year duration. She also complained of dysphagia, nasal regurgitation, decreased vision in both the eyes since 4-5 years. There was no history of exposure to organic or inorganic dust or history suggestive of collagen vascular disease. She had been evaluated for these symptoms and in view of parotid swelling cytology suggestive of tuberculous inflammation started on anti tuberculosis drugs, but without any relief of symptoms.
We assessed her and on further examination found to have right-sided VII, IX, X, XI cranial nerve palsy. Hematological investigations were normal. X-ray chest showed bilateral ground glass opacities. Sputum was negative for acid-fast bacilli. Sputum culture did not grow any organism. Parotid swelling cytology showed epitheloid cell granuloma with caseous necrosis. Ophthalmologic examination for fundus was normal. Ultrasonography of abdomen showed splenomegaly. Tuberculin skin test was negative. Computed tomography (CT) thorax showed interlobular and intralobar septal thickening involving bilateral lung fields with mediastinal lymphadenopathy, which showed homogenous enhancement following contrast injection. Magnetic Resonance Imaging (MRI) brain performed in view of cranial nerve palsy showed cerebral and cerebellar atrophy but no focal abnormality. Angiotensin Converting Enzyme (ACE) levels were 145 units, elevated and gallium scan showed focal accumulation of gallium in right hilar region with no other abnormal focal uptake elsewhere in the body which was typical of sarcoidosis [Figure 1], confirming the diagnosis of sarcoidosis. Antituberculosis therapy was stopped and oral corticosteroid therapy initiated with improvement in symptoms.
| Discussion|| |
Sarcoidosis is a chronic inflammatory disease commonly found in the lungs, hilar lymph nodes, but multiple organs could be involved. Recent International Consensus Statement recommendations regarding diagnosis of sarcoidosis are based on a compatible clinical and/or radiological picture, histological evidence of noncaseating granulomas and exclusion of other diseases capable of producing a similar histological or clinical picture.
It is defined in terms of the microscopic appearance, one of the main features being the absence of caseation in the granuloma. In lymph node the granulomata are often large and confluent, particularly in the early stage of hyalization, diffuse sheets of granulation tissue are seen. It is not strange that granular necrosis may be seen at some stage in the evolution of sarcoid lesion, as initially the lesion is highly cellular being replaced by hvaline which often first appears centrally in granuloma. 
Although non-necrotizing granulomas are the usual findings in sarcoidosis, necrosis does occur. Prior to the widespread use of transbronchial biopsy necrosis was reported in up to 30% of large biopsy specimens (open lung, lymph node). The incidence of necrosis is far lower in small specimens such as transbronchial biopsies because of the small number of granulomas usually sampled. Compared with the necrosis seen in infectious granulomas the necrosis in the granulomas of sarcoidosis is most often focal, very small in size and involves very few of the granulomas. The foci of necrosis are acidophilic with a fibrinoid, granular appearance and usually located within the centers of granulomas. Rarely, biopsy material from patients with well documented sarcoidosis will exhibit extensive necrosis resemblins that seen in infectious and other granulomataus processes.  This necrosis has the same appearance in a microscopic section as "caseation necrosis" that peculiar form of necrosis which Cameron (1951) described as cheesy or milky by reference to the naked eye appearance. In sarcoidosis these necrotic areas are small and unrecognizable to the naked eye. Histologically it is possible to distinguish between granular necrosis found in sarcoidosis and the caseation of tuberculosis. Hyaline material may at first sight resemble caseous material because it is relatively acellular, eosinophilic and may merge with very active granulation tissue in sarcoidosis. Special stains like Van Giesen will identify collagen and this together with reticulin stain such as Gomori's stain will help in diagnosis, where as haematoxylin - eosin stained section fails to do so. 
In our case, although a diagnosis of tuberculosis was made initially based on cytology showing granuloma with caseation necrosis [Figure 2], the long duration of illness, its response to steroids, negative sputum cultures exclude an infectious etiology. We could not perform special staining for the specimen. However, multisystemic sarcoidosis could be diagnosed in view of homogenously enhancing mediastinal lymphadenopathy on CT-Thorax, tuberculin skin test negativity, elevated ACE levels, nerve palsies.
Various studies have reported caseation in subcutaneous tissue  and henatic  specimens in sarcoidosis patients. Longcope and Freiman, after examination of autopsy material reported that it is necessary to accept certain amount of 'granular necrosis' as consistent with sarcoidosis. They describe this form as spotty, rarely involving more than a few scattered lesions and strictly limited to the central portion of the granulomatous foci. They stressed the value of reticulin stain as it demonstrates reticulin passing right through the area of necrosis. Hence, necrosisresembling caseation should be excluded by the use of stains for collagen and reticulin.
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[Figure 1], [Figure 2]