Subepidermal Calcinosis
Key Points
Subepidermal calcinosis is a form of localized cutaneous soft tissue calcium deposit
It is classified as dystrophic, metastatic, calciphylaxis, iatrogenic, and idiopathic types
The pathogenesis is poorly understood, and of the various causes proposed, none are supported by convincing evidence
Clear clinical characteristics are generally absent so that the diagnosis is usually made only after histopathologic examination
Lesions appear as a round to oval; painless; yellow, white, gray, or pink; solitary; mobile; hard nodule located in the upper dermis of the skin
The definitive treatment is not established, but complete surgical excision has been the treatment of choice in most reports
The prognosis is excellent following surgical excision, even when the resection is incomplete
Subepidermal calcinosis (SC) is a form of soft tissue calcium deposit that was first recognized by Winer in 19521 and later named by Woods and Kellaway in 1963.2 A wide variety of synonyms have been used in the literature including idiopathic calcinosis cutis, localized cutaneous calcinosis, subepidermal calcified nodule, cutaneous calculi, and solitary nodular calcification.3,4
SC is classified as dystrophic, metastatic, calciphylaxis, iatrogenic, and idiopathic types.5 Dystrophic calcification is the most common form and usually occurs in association with autoimmune and other diseases that cause chronic inflammation and alterations within connective tissue.4 Metastatic calcification is characterized by abnormal calcium and or phosphate metabolism.4 Calciphylaxis refers to calcification in the media of small and medium-sized dermal blood vessels and subcutaneous tissues sometimes seen in end-stage renal disease.6 Idiopathic SC occurs in otherwise healthy individuals without any associated systemic disease, abnormal laboratory studies, or history of trauma.7,8,9,10,11,12,13
Subepidermal calcinosis is a rare dermatological condition with only about 150 cases described in the literature. Of these, fewer than 60 cases have involved the ocular adnexa.9,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28 Among the eyelid lesions, there is a marked male predominance of about 67%.3 These lesions have been seen in patients aged from 3 to 90 years, but about 90% occur in patients ≤21 years of age, and the mean age at presentation is about 12 years.5 About 42% of reported cases occurred in Caucasian, 24% in Hispanic, 21% in black, and 13% in Asian patients.3
Etiology and Pathogenesis
The pathogenesis of subepidermal calcinosis is poorly understood, but numerous possible etiologies have been proposed. Dystrophic calcification that forms in devitalized tissues or in preexisting lesions within the connective tissue of the dermis following trauma seems unlikely for many cases because there is no consistent history of trauma.5,29 Calcified lesions have been associated with syringomas and milia,20,30 especially in patients with Down syndrome,31 but this association is rare. Nanobacterial activity has been proposed as a cause, but ultrastructural analysis of a series of dystrophic calcifying conditions of the skin failed to show any evidence of nanobacteria.32 A hypersensitivity reaction followed by degranulation of mast cells with subsequent deposition of calcium and phosphate has also been proposed,33,34,35 but there is little evidence to support this view. Another proposal suggested that SC might arise from calcification of sweat ducts or hair follicles.28
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