Sarcoidosis, a systemic disease distinguished by noncaseating granulomatous inflammation of various tissues, can present with cutaneous manifestations. Various skin lesions - papules, pustules, plaques, macules, etc., including erythema nodosum and lupus pernio, may constitute the clinical presentation of cutaneous sarcoidosis. A working hypothesis, laboratory tests, identification of additional signs and symptoms, and biopsy of the skin are essential steps in making the diagnosis.
Sarcoidosis, a multisystemic disease of unknown etiology, may involve virtually any organ in the body, including the lungs, lymph nodes, liver, spleen, eyes, etc. [1] [2] [3]. In approximately 25-35% of patients, it can cause skin-related symptoms, in which case the term cutaneous sarcoidosis is used [3] [4] [5]. Furthermore, reports show that cutaneous signs of the disease are the only manifestation in 3-5% of patients [4] [5]. Numerous skin lesions have been reported in the literature, but the two most common and most important are [3] [6]:
In addition to erythema nodosum and lupus pernio, single or multiple papules or plaques of different sizes and colors (red, brown, hypopigmented or even translucent) developing on the face and the extremities, either as isolated lesions or in a confluent pattern are other notable manifestations of this disease [2] [6]. In some cases, the term is used to denote the appearance of the lesion in a preexisting scar (scar sarcoidosis) [6].
As cutaneous sarcoidosis possesses numerous types of lesions, it might be difficult to establish a diagnosis solely on clinical criteria. Nevertheless, the initial suspicion towards this inflammatory disease can only be raised after a thorough physical examination and a meticulously obtained patient history [4] [6]. This condition often (but not always) precedes involvement of other organs and systemic symptoms, thus the detection of associated lesions is perhaps the only tool in making a presumptive diagnosis. Given the systemic nature of the disease, a thorough laboratory workup should be performed, comprising liver and kidney function tests, serum inflammatory markers, and angiotensin-converting enzyme (ACE) [1] [6]. In addition, chest radiography, pulmonary function tests, electrocardiography (ECG), and a complete ophthalmologic exam are recommended in the workup [6]. To confirm the diagnosis of cutaneous sarcoidosis, however, biopsy of the skin with subsequent histopathological examination is the gold standard [1]. A punch biopsy allows a satisfying amount of tissue to be obtained, and the presence of non-caseating granulomas is virtually a pathognomonic finding of sarcoidosis [1] [5].