Sarcoidosis.

 

Sarcoidosis

PKGhatak, MD

In the old days of pulmonary tuberculosis, sarcoidosis was an interesting entity and entered into the differential diagnosis of pulmonary tuberculosis. Nowadays, sarcoidosis had taken that spot in the differential diagnosis of granulomatous diseases. This distinct applied to sarcoidosis because the cause of sarcoidosis is unknown, it can and usually affect multiple organs. Sarcoidosis may be self-limited or progressive or chronic. Sarcoidosis passes through three stages – inflammation, granuloma formation, fibrosis. Many other diseases have similar pathological characteristics. In short, sarcoidosis is diagnosed when all known causes of a granulomatous disease are eliminated.

Granuloma is a tiny localized collection of densely packed immune cells mostly macrophages, and epithelioid cells (elongated nucleus of macrophages), and a few Langhans giant cells (fusion of macrophages) surrounded by a zone of lymphocytes, eosinophils with some fibrosis at the periphery. The distinctive features of sarcoid granuloma are asteroid body- eosinophilic star shaped structures, and rounded laminated partially calcified structures called Schaumann bodies. The foreign-body granuloma at the center of the granuloma contains a part of the foreign body. Sarcoid granuloma is described as Non-Caseating granuloma. In the case of tuberculosis, the bacterial toxin causes the death of cells and matted dead cells are called caseation.

Sarcoidosis is due to the response of the Immunocytes to foreign agents/antigens. But the identity of the antigen and mechanism of the derailed function of Immune cells are not known. The hallmark of sarcoid is a granuloma. Immune cells fail to destroy the foreign antigen but contain it locally by forming a dense cellular wall around it.

 Common granulomatous diseases:

Foreign body – wood splinters, metal fragments, insect stings, spider bites. The ingrown root of the hair, tattoo ink, inhaled beryllium, dermal fillers collagen, forgotten sutures, aspiration of food particles in the lung.

Granulomatous polyangiitis or Wagner granulomas. - granuloma forms in the nasal passage, trachea, major bronchi. Hemoptysis is the presenting symptom.

Eosinophilic polyangiitis also called Churg-Struss syndrome, Necrotizing vasculitis of small and medium size vessels with peripheral eosinophilia and ANCA positive vasculitis. Patients present with asthma, weight loss and polyneuritis, bronchitis and other systemic symptoms.

Crohn's disease –  A chronic granulomas ulcerative lesion of the colon and terminal ilium and anal canal.

Rheumatic fever. Streptococcal antigen triggers granulomas on heart valves.

Rheumatoid arthritis. It is a debilitating chronic arthritis of the small joints of fingers, cervical spine, and knees; occasional granulomas in pleura and pulmonary fibrosis.

Mycobacteria infection. - Pulmonary tuberculosis, non-MT granulomatous diseases, Leprosy.

Bacterial. - Cat- scratch fever, Listeriosis,

Fungus. - Histoplasma, coccidoiodocomyces, blastomycosis, Cryptococcus.

Parasites. -Leishmaniosis of skin, liver and spleen; pneumocystis.

Symptoms of sarcoidosis are variable based on organ involvement:

Pulmonary lesions are 1. Hilar adenopathy in young adults must be differentiated from sarcoma by CT scan of the chest and abdomen and mediastinoscopy biopsy.2. Pulmonary infiltrates with or without adenopathy resembling pulmonary tuberculosis. Interferon gamma release assay, sputum smear and cultures for AFB and rarely bronchoscopic biopsy may be required. 3. Cavitary pulmonary lesion presented with hemoptysis. 4. Extensive pulmonary fibrosis and loss of lung tissue.

Skin: Lesions are. 1. Lupus pernio. - Disfiguring lesions of nose, cheeks, lips.2. Granuloma annuaries - flesh colored raised skin lesions on bony prominences and characterized by multiple rings. 3. Polyarteritis nodosa. - Raised painful nodules purplish blue color, appear in crops on the lower legs over the shin bones.

Heart. Heart block and other conduction abnormalities. Diagnosis is difficult if only a heart block is present. Liver biopsy is often diagnostic.

Eye. - Uveitis, chorioretinitis, sclerites, blindness. Dry eyes. Lachrymal gland biopsy may be required.

CNS. Facial nerve palsy is also called Bell's palsy, various neurological symptoms based on stages of the disease of CNS. Meningitis, seizures, dementia, polyneuropathy.

Kidneys. Recurrent renal stones.

Bones. Osteoporosis.

Blood. High calcium and markedly raised ACE (angiotensin converting enzyme), high ACE is also present in other granulomas but usually in the modest range. ACE is produced by granuloma cells.

Common symptoms at the time of presentation. The symptoms vary according to the organ involved. In the young adult male, hilar lymphadenopathy is usual. In general, the condition resolves spontaneously in 6 weeks. Recurrent skin lesions are common in blacks. Various eye lesions maybe not be so obvious initially but in chronic lesions, the eye involvement is usual. Dry eyes may require a biopsy of lachrymal glands for a diagnosis. Cavitary and progressive pulmonary fibrosis have a poor prognosis.

Treatment:

Treatment is urgent when eyes, heart CNS sarcoid lesions are present. Hypercalcemic may require emergency medical therapy.

Prednisone is the primary drug. Because of major side effects Methotrexate, Leflunomide, Hydroxychloroquine, Imuran, and cytotoxic drugs are added while the dose of prednisone is decreased or stopped.

Prognosis: Asymptomatic hilar lymphadenopathy has the best prognosis. Processive fibrosis has the worst outcome.

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