SkIndia Quiz 34: Asymptomatic Swelling over an Old Forehead Scar.

Scar sarcoidosis.

Sarcoidosis is a multisystem disorder of unknown etiology characterized by the formation of noncaseating epitheloid granulomas composed of lymphocytes and mononuclear phagocytes leading to derangement of anatomy and function of the tissues in which they accumulate. The incidence of sarcoidosis varies among countries and different ethnic groups.[ 1 ] The most commonly affected organs are the lungs, lymph nodes, and eyes. Cutaneous involvement is seen in approximately 20%–35% patients of sarcoidosis, whereas exclusive cutaneous involvement is seen in only 2% of cases.[ 2 ] Cutaneous sarcoidosis is polymorphic and can manifest with specific and nonspecific lesions. Erythema nodosum is the only nonspecific manifestation of sarcoidosis, which is the hallmark of acute and benign disease. The specific lesions, lupus pernio and plaques are associated with more severe systemic involvement and a more chronic course. Scar sarcoidosis is a specific manifestation of sarcoidosis, occurring in 5.4%–13.8% adult patients of cutaneous sarcoidosis.[ 3 ] It has been reported at the scar sites of pseudofolliculitis barbae, herpes zoster, Kveim test, tuberculin test, hyaluronic acid injection, venipuncture, tattoos, mechanical trauma, and postradiation. Contamination of scar with foreign material possibly at the time of trauma has been proposed as the likely pathogenesis of sarcoidal granulomas. Scar sarcoidosis presents as reappearance of edema and erythema at the site of an old burnt-out scar. The lack of pruritus differentiates scar sarcoidosis from its clinical mimickers, namely, hypertrophic scar and keloid. The diagnosis can be confirmed by biopsy after the exclusion of other causes such as infectious disease, foreign body granulomas, neoplasias, and other granulomatous processes. Cutaneous sarcoidosis may be isolated or precede systemic sarcoidosis, most commonly pulmonary sarcoidosis. It may accompany the pulmonary changes during the acute phase or occur in the late phase as a sign of exacerbation/recurrence in a previously quiescent sarcoidosis.[ 4 ] In patients of cutaneous scarcoidosis having systemic involvement, iritis is seen much more commonly in scar sarcoidosis (84.6%) as compared to other forms of cutaneous sarcoidosis (30%).[ 4 ] Majority of the patients with cutaneous sarcoidosis develop systemic involvement either at the onset or in long-term follow up. A periodic evaluation including physical examination, complete blood count, serum calcium, renal and hepatic function tests, chest radioimaging, pulmonary function tests, electrocardiogram, and ophthalmological evaluation is recommended for all patients.[ 5 ] At follow-up visits, it is important to keep an eye on scars for any signs of new activity, as biopsy of these scars can easily be performed and can avoid the more invasive investigations to establish the diagnosis of sarcoidosis with systemic involvement. The prognosis of patients with cutaneous sarcoidosis depends on the extent of systemic involvement.[ 6 ] As the extent of cutaneous lesions does not correlate with that of systemic involvement and many of the patients have spontaneous remissions, systemic treatment is indicated for cutaneous disease only if it is progressive and disfiguring. Intralesional corticosteroids and high-potency topical corticosteroids are usually employed for cutaneous lesions. Excision of small lesions may be done but there is a risk of inducing sarcoidal infiltrates. Other therapies that have been used include anti-inflammatory and immunosuppressive drugs, chloroquine, isotretinoin, allopurinol, thalidomide, and tetracyclines; and carbon dioxide laser.[ 7 ]