Stage 3 is characterized by reticulonodular infiltrates alone; spontaneous resolution is less common.
Stage 4 manifests pulmonary fibrosis which may result in progressive dyspnoea, pulmonary hypertension and cor pulmonale.
Skin lesions
The skin is involved in about 25% of patients by one of the following:
1Erythema nodosum is characterized by tender erythematous plaques typically involving the knees and shins (see Fig. 11.15A) and occasionally the thighs and forearms.
2Granulomatous scattered papules, plaques or nodules.
3Lupus pernio consists of indurated, violaceous lesions involving exposed parts of the body such as the nose, cheeks, fingers and ears (Fig. 11.15D).
4Granulomatous deposits in long-standing scars or tattoos.
Other manifestations
1Neurological disease affects 5–10% of patients. The most common lesion is unilateral facial nerve palsy (see Fig. 11.15C); less common manifestations include seizures, meningitis, peripheral neuropathy and psychiatric symptoms.
2Arthritis in chronic sarcoidosis is typically symmetrical and may involve both small and large joints. In children the presentation can be very similar to JIA because arthropathy tends to be more prominent than pulmonary disease.
3 Bone cysts typically involve the digits and are associated with swelling.
4Renal disease in the form of nephrocalcinosis, hypercalciuria and calculi.
5Miscellaneous manifestations include lymphadenopathy, granulomatous liver disease, splenomegaly and cardiac arrhythmias.
Investigations
1Chest radiographs are abnormal in 90%.
2Biopsy
•Lungs give the greatest yield (90%) even in asymptomatic patients with normal chest radiograms.
•Conjunctiva is positive in about 70% of patients with granulomatous inflammation in the form of nodules, which resemble those of follicular conjunctivitis.
•Lacrimal glands are positive in 25% of un-enlarged and 75% of enlarged glands (Fig. 11.15E).
•Superficial lymph node or skin lesion.
3Enzyme assay for serum angiotensin-converting enzyme (ACE) and lysozyme as already described.
4Bronchoalveolar lavage shows a raised proportion of activated T-helper lymphocytes. Sputum examination may also show increased CD4/CD8 ratios.
5Pulmonary function tests reveal a restrictive lung defect with reduced total lung capacity and are very useful for monitoring disease activity and the need for systemic therapy.
6Mantoux test is negative in most patients; a strongly positive reaction to one tuberculin unit makes the diagnosis of sarcoidosis highly unlikely.
Ocular features
Uveitis is the most common and may be in the form of anterior, posterior or intermediate. Other manifestations include KCS, conjunctival nodules, and rarely, orbital and scleral lesions.
1AAU typically affects patients with acute-onset sarcoid.
2CAU, typically granulomatous (see Figs 11.4B and 11.5), tends to affect older patients with chronic pulmonary disease.
•Iris nodules may be very large (Fig. 11.16A).
•The trabecular meshwork may show nodules (Fig. 11.16B) and tent-shaped peripheral anterior synechiae.
3Intermediate uveitis with snowballs (Fig. 11.16C) or string-like opacities is uncommon and may antedate systemic disease. The presence of associated granulomatous anterior uveitis should arouse suspicion.
4Periphlebitis
•Yellowish or grey-white perivenous sheathing that may also involve the optic nerve head (Fig. 11.17A).
•Occlusive periphlebitis is uncommon (Fig. 11.17B).
•Perivenous exudates referred to as ‘candlewax drippings’ (en taches de bougie) are typical of severe sarcoid periphlebitis (Fig. 11.17C).
5Choroidal infiltrates are uncommon and vary in appearance:
•Multiple small pale-yellow infiltrates, which may have a ‘punched-out’ appearance, and are often most numerous inferiorly are the commonest (Fig. 11.18A).
•Multiple large confluent infiltrates which may have amoeboid margins are less common (Fig. 11.18B).
•Solitary choroidal granulomas are the least common (see Fig. 11.6B).
6Multifocal choroiditis (Fig. 11.18C) carries a guarded visual prognosis because it may cause loss of central vision as a result of secondary CNV which may be peripapillary or associated with a chorioretinal scar.
7Retinal granulomas are small discrete yellow-white lesions (Fig. 11.18D).
8Peripheral retinal neovascularization may develop secondary to retinal capillary dropout. In black patients it may be mistaken for proliferative sickle-cell retinopathy.
9 Optic nerve involvement may take the following forms:
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