Skin changes in sarcoidosis

Overview

•Sarcoidosis - multisystem granulomatous disease; skin involved in ~25-35% of cases

•Cutaneous lesions divided into specific (contain non-caseating granulomas) and non-specific (reactive, no granulomas)

Presentation

•Lupus pernio - violaceous (purple-red), indurated plaques on nose, cheeks, ears, lips; strongly associated with chronic systemic sarcoidosis (pulmonary fibrosis, bone cysts, uveitis); specific lesion

•Maculopapular eruption - most common specific lesion; small red-brown papules around periorbital skin, nasolabial folds, mouth

•Scar sarcoidosis - pre-existing scar or tattoo becomes raised, indurated, and purple; highly specific clinical clue

•Subcutaneous nodules (Darier-Roussy) - deep, painless, flesh-coloured nodules on trunk and extremities

•Erythema nodosum - tender, warm, erythematous nodules on shins (anterior); bilateral; do not ulcerate; fade to bruise-like hue over 4-6 weeks; non-specific lesion

🎯
Löfgren syndrome - erythema nodosum + bilateral hilar lymphadenopathy + uveitis + polyarthralgia (ankle arthritis) = acute sarcoidosis; excellent prognosis, remission rate ~80-90% without treatment.

Investigations

🥇 First-line

•Skin biopsy of specific lesion - non-caseating epithelioid granulomas, no central caseation (gold standard)

•Chest X-ray - bilateral hilar lymphadenopathy (most common systemic finding)

•Serum ACE - elevated in ~60% of active disease; useful for monitoring, not diagnostic alone

•Serum/urinary calcium - hypercalcaemia from granuloma-mediated 1-alpha-hydroxylase activity

🥈 Second-line

•CT chest, ophthalmology slit-lamp (uveitis), pulmonary function tests

⚠️
Always exclude TB before starting immunosuppression - both cause granulomas and erythema nodosum. Key histological difference: caseating necrosis in TB vs no necrosis in sarcoidosis. Perform tuberculin skin test and/or IGRA first.

Differential diagnosis

Key differentials for facial/granulomatous skin lesions
ConditionKey featuresDistinguishing point
Discoid lupus erythematosusErythematous plaques, central atrophy, follicular plugging, scarring on sun-exposed areasPhotosensitivity; positive ANA/anti-dsDNA; no granulomas
RosaceaFacial erythema, papules, pustules, telangiectasia on nose and cheeksNo granulomas on biopsy; no systemic disease
Cutaneous TB (lupus vulgaris)Granulomatous skin lesionsCaseating granulomas; positive IGRA/tuberculin test
Granuloma annulareAnnular skin-coloured papules on hands/feetNo systemic involvement; palisading granulomas on biopsy

Condition	Key features	Distinguishing point
Discoid lupus erythematosus	Erythematous plaques, central atrophy, follicular plugging, scarring on sun-exposed areas	Photosensitivity; positive ANA/anti-dsDNA; no granulomas
Rosacea	Facial erythema, papules, pustules, telangiectasia on nose and cheeks	No granulomas on biopsy; no systemic disease
Cutaneous TB (lupus vulgaris)	Granulomatous skin lesions	Caseating granulomas; positive IGRA/tuberculin test
Granuloma annulare	Annular skin-coloured papules on hands/feet	No systemic involvement; palisading granulomas on biopsy

Management

•First-line (localised specific lesions): Topical or intralesional triamcinolone - reduces granulomatous inflammation in lupus pernio, plaques, papules

•First-line (erythema nodosum/Löfgren): Ibuprofen (NSAIDs) + rest - self-limiting, resolves within ~6 weeks

🥈 Second-line

•Oral prednisolone 20-40 mg daily, tapered over months - for extensive/symptomatic specific disease or systemic involvement

•Hydroxychloroquine - for skin-predominant disease; requires regular ophthalmological monitoring

🥉 Third-line

•Methotrexate or azathioprine (steroid-sparing); infliximab (anti-TNF-α) for refractory disease