Mobile Subcutaneous Calcinosis Cutis: A Case Report of a Mobile Solitary Subepidermal Calcified Nodule on a Woman's Leg and a Review of Mobile Subcutaneous Tumors

Abstract

Calcinosis cutis describes the deposition of calcium in the dermis. A case of a 69-year-old woman with idiopathic calcinosis cutis that presented as a mobile subcutaneous nodule is described. The patient had an asymptomatic, firm, mobile subcutaneous nodule on her right lower leg of at least six months duration. The nodule could be easily moved from one location to another. An incisional biopsy was performed. Microscopic examination of the tissue specimen showed islands of basophilic calcium material in dense sclerotic dermal connective tissue establishing the diagnosis of calcinosis cutis. Mobile solitary calcification is an unusual presentation of idiopathic calcinosis cutis. In addition to idiopathic calcinosis cutis, benign mobile subcutaneous tumors have also been derived from adnexal structures of hair follicles and adipose tissue. Hence, not only idiopathic calcinosis cutis, but also subepidermal calcinosis in the ocular adnexa, proliferating trichilemmal cyst with focal calcification, and mobile encapsulated adipose tissue can present as a mobile subcutaneous nodule. The features of idiopathic calcinosis presenting as a mobile subcutaneous nodule as well as the characteristics of other benign mobile subcutaneous tumors are reviewed.

Keywords: calcified; calcinosis; calcinosis cutis; cutaneous; cutis; disease; mobile; nodular; subcutaneous; subepidermal.

Figure 1. Clinical presentation of a mobile subepidermal calcified nodule.

The pretibial right leg of a 64-year-old woman shows the original proximal location of the subcutaneous nodule (red arrow pointing to site demarcated by thin lines of black ink) and the distal location 5.5 centimeters away to which it has moved (thick black arrow pointing to subepidermal nodule demarcated by thin lines of black ink). The site of her prior keratoacanthoma appears as a red-purple-colored patch (within the black oval).

Figure 2. Incisional biopsy of proximal right pretibial leg

A 7 millimeter incision was performed on the proximal pretibial right leg of the woman with the mobile subcutaneous nodule. A 3 x 1 millimeter yellow firm nodule was expressed from the proximal edge of the incision (black arrow).

Figure 3. Microscopic presentation of a mobile subepidermal calcified nodule

Distant (A) and closer (B, C, and D) views of the tissue specimen show a circumscribed nodule surrounded by dense sclerotic connective tissue with islands of basophilic calcium (black arrows) (hematoxylin and eosin: A, x 2; B, x 10; C, x 20; D, x 40).