42
Calcinosis Cutis and Osteoma Cutis
There are four major forms of cutaneous calcification (calcinosis cutis): (1) dystrophic – locally within sites of pre-existing skin damage; (2) metastatic – due to systemic metabolic derangements; (3) iatrogenic – secondary to medical treatment or testing; and (4) idiopathic. Cutaneous ossification (osteoma cutis) occurs in the setting of several genetic disorders, in a miliary form on the face and within neoplasms and sites of inflammation (secondary).
Calcinosis Cutis
Calcinosis Cutis – Dystrophic
• Often seen in autoimmune connective tissue diseases (AI-CTDs), in particular the limited form of systemic sclerosis (also referred to as CREST syndrome) and childhood dermatomyositis (Figs. 42.1 and 42.2); in the former, hard, skin-colored to white papules overlie the bony prominences of the extremities (upper > lower), whereas in the latter the deposits are often larger and sometimes plate-like.
Fig. 42.1 Dystrophic form of calcinosis cutis. Note the cluster of small white papules in this patient with the limited form of systemic sclerosis (also referred to as CREST syndrome). Courtesy, Janet Fairley, MD.
• Extrusion (transepidermal elimination or ‘perforation’; see Ch. 79) of the calcium deposits appears as a white chalky material and it can be followed by a persistent ulceration.
• Other underlying causes are listed in Table 42.1.
