Sarcoidosis

What it is

Sarcoidosis is a multisystem granulomatous disorder of unknown etiology. The pathology is noncaseating granulomas in involved organs. The common presentations are bilateral hilar lymphadenopathy, pulmonary reticular opacities, that is ILD, and skin, joint and/or eye lesions.

Among the diseases predominantly affecting the upper lobes it is listed with upper and middle lobe disease, non-caseating granulomas, and bilateral hilar lymphadenopathy as its key features.

How it presents

The systemic review names sarcoidosis three times: with inflammatory arthritis, with ocular symptoms, and with skin lesions. The same review sets out the other causes of those, since dry eyes and dry mouth point to Sjogren's, Raynaud's and difficulty swallowing to scleroderma and other CTD, and proximal muscle weakness and skin to polymyositis and dermatomyositis. Inflammatory arthritis and skin lesions are listed with CTD as well, so one alone is not enough.

The written case is a 50 years old female with progressive dry cough and constitutional symptoms, in whom O/E shows erythematous, nonulcerated and tender nodules over the bilateral shins. Those nodules are erythema nodosum, the chest radiograph shows bilateral hilar adenopathy, and the diagnosis is sarcoidosis.

Erythema nodosum itself is inflammation of subcutaneous fat, giving tender, erythematous, nodular lesions usually over the shins though they may occur elsewhere such as the forearms and thighs; it usually resolves within 6 weeks and heals without scarring, and it is self-limited over 2-8 weeks but may recur. Its causes run wider than this disease: infection with streptococci, TB or brucellosis; systemic disease, that is sarcoidosis, inflammatory bowel disease and Behcet's; malignancy or lymphoma; drugs, that is penicillins, sulphonamides and the combined oral contraceptive pill; and pregnancy. When two underlying causes are asked for, the pair given is streptococcal throat infection and sarcoidosis.

One further presentation belongs here by its picture rather than its organ: a young female with SOB and low grade fever whose chest radiograph shows a wide mediastinum and bilateral hilar lymphadenopathy.