Page 387 - Concise Pathology for Exam Preparation ( PDFDrive )

372 SECTION II Diseases of Organ Systems

Environmental Contribution

Several microbes have been implicated in the pathogenesis of sarcoidosis, eg, Mycobacteria,
Propionibacterium acnes, Borrelia burgdorferi, viruses, fungi and Rickettsia species.

Morphology
• Involved tissues show noncaseating granulomas composed of closely packed epithelioid
cells with Langhans or foreign body giant cells (lymphocytes are few in number, so
granulomas also called ‘naked granulomas’).
• Long-standing granulomas are enclosed within fibrous rims or hyaline scars and may
show the following inclusions:
• Laminated concretions composed of calcium and proteins known as Schaumann
bodies
• Stellate inclusions in giant cells called asteroid bodies
1. Lungs
(a) Most commonly involved; show granulomas which coalesce to produce small pal-
pable nodules around lymphatics, bronchi, blood vessels and sometimes within
alveoli; heal with fibrosis
(c) Pleural surfaces may sometimes be involved
2. Lymph nodes
(a) Involved in almost all cases; sarcoidosis mainly affects hilar and mediastinal nodes,
may occasionally manifest as generalized lymphadenopathy
(b) Nodes are enlarged, discrete, nontender and sometimes calcified.
(c) Tonsils may also be involved in some cases.
3. Spleen
(a) Microscopic involvement of spleen is seen in three-fourth cases but gross enlargement
is seen in very few cases
(b) Contains scattered granulomas
4. Liver
(a) Involved less often than spleen
(b) Shows scattered granulomas located more often in the portal triads than the lobular
parenchyma
5. Bone marrow
(a) Typically involves the phalangeal bones creating small-circumscribed areas of lysis.
(b) Widening of bony shafts and new bone formation on the outer surfaces may be
seen.
6. Skin and mucosa
(a) Skin lesions are encountered in about 50% cases.
(b) Include discrete subcutaneous nodules; erythematous plaques or red scaly flat lesions.
(c) Lesions may also appear in the mucous membranes of oral cavity, larynx and upper
respiratory tract.
7. Eye
(a) May cause iritis or iridocyclitis, corneal opacities, glaucoma and total loss of vision.
(b) Inflammation of lacrimal glands and suppression of lacrimation are commonly
encountered.
8. Salivary glands
(a) Bilateral involvement of the salivary glands is usual.
(b) Combined uveoparotid involvement is labelled Mikulicz syndrome.
9. Muscle: Involvement of muscle manifests as muscle weakness, tenderness and fatigue.
Sarcoid granulomas may also be seen in CNS, endocrine organs, kidneys and heart.

Clinical Features
• Usually discovered accidentally on routine X-ray or CT scan
• Insidious onset of respiratory symptoms (shortness of breath, cough, chest pain and
haemoptysis)

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