Subepidermal calcified nodule (nodular calcinosis of Winer)

Abstract

Subepidermal calcified nodule (SCN) is a clinical form of idiopathic calcinosis cutis, which commonly affects children, and presents as yellowish-white lesions involving the face. It is often misdiagnosed for other disorders like warts and molluscum contagiosum and treated by ablative procedures. In such a scenario, lack of histopathological examination makes it difficult to reach the correct diagnosis. We here report a case of SCN which was diagnosed after an excisional biopsy. Further, histopathological finding of dermal calcium deposits must prompt the clinician to rule out other disorders leading to calcinosis cutis, before labelling the case as SCN.

Background

Calcinosis cutis (CC) is an abnormal deposition of calcium in the skin or subcutaneous tissue and can be categorised into five subgroups: dystrophic, metastatic, iatrogenic, calciphylaxis and idiopathic.¹ Subepidermal calcified nodules (SCNs) are an uncommon form of idiopathic CC (ICC) that is commonly seen in children and present as yellowish-white lesions. They are often mistaken for other disorders like wart, molluscum contagiosum and appendageal tumours.² We here report a case of SCN which was diagnosed and treated by an excisional biopsy.

Case presentation

A man in his 20s presented with a history of a single, asymptomatic, whitish lesion over the right side of the face for the past 2 years. On examination, a single, well-demarcated, yellowish-white, hard nodule measuring approximately 1.5×1 cm in size was present over the right eyebrow at the junction of medial one-third and lateral two-thirds (figure 1). There was no history of trauma to the affected area and no signs and symptoms suggestive of any systemic illness and connective tissue disorders.

Figure 1.

A single, asymptomatic, whitish lesion over the right eyebrow (red arrow).

Investigations

An excisional biopsy was performed and histopathological examination revealed areas of hyperkeratosis, acanthosis and dense, acellular deposits of dark blue material in the dermis (figures 2 and 3A). Special staining with Von Kossa stain confirmed these deposits to be of calcium salts (figure 3B).

Figure 2.

Histopathological examination showing dense deposits of dark blue basophilic material in the dermis (H&E, 4×).

Figure 3.

(A) Dense basophilic deposits in the dermis (H&E, 10×). (B) Von Kossa stain demonstrating black-coloured calcium deposits in the dermis (10×).

The patient was therefore diagnosed as a case of CC and was evaluated for any underlying metabolic abnormality. Levels of serum calcium, phosphorus, alkaline phosphatase, vitamin D, parathormone and kidney function tests were within normal limits. Anti-nuclear antibody was negative.

Differential diagnosis

In view of the site, morphology and hard consistency, CC was considered as the first clinical differential diagnosis. However, it was essential to rule out other diseases like verruca vulgaris and various tumours of the cutaneous appendages. The definite diagnosis was established by an excisional biopsy of the lesion which was both diagnostic and curative. Histopathology revealed extensive deposits of calcium in the dermis, consistent with the diagnosis of CC. Pilomatricoma, which often presents with calcification on histopathology, was ruled out by the absence of basaloid cells and ghost (shadow cells. Further, it was essential to rule out the type and cause of CC. Our patient presented with a single, asymptomatic lesion on the face. There was no history of associated trauma or pre-existing tumour. On detailed evaluation, there was no evidence of any metabolic disorder, underlying connective tissue disorder or malignancy. Therefore, this case of CC was classified under the idiopathic category as an SCN, also called as Winer’s nodular calcinosis.

Treatment

Excisional biopsy was done to confirm the diagnosis, and it was also curative for this case.

Outcome and follow-up

There has been no recurrence of the lesion at the site of the previous lesion for 1 year after the excision. Also, no other lesion at any other site has been noted so far.

Discussion

CC is characterised by the deposition of insoluble calcium salts in the skin and subcutaneous tissue. The syndrome is divided into five subtypes: dystrophic calcification, metastatic calcification, idiopathic calcification, iatrogenic calcification and calciphylaxis.¹

Calcification in the skin and/or subcutaneous tissues with no identifiable cause is labelled as ICC. It appears without any underlying tissue damage or metabolic disorder.^{1 2} Since there was no evidence of any underlying metabolic disorder, connective tissue disorder or malignancy, the present case was labelled as ICC. ICC includes three clinical forms: tumorous calcinosis, SCN and scrotal calcinosis.¹

Tumorous calcinosis is characterised by the deposition of calcific masses around major joints. It occurs in otherwise healthy adolescents. The calcified deposits are subcutaneous or intramuscular and may impair joint function. The overlying skin is usually unaffected, but ulceration and skin calcification can occur. It has been found to be associated with hyperphosphataemia.¹

Scrotal calcinosis presents as nodules and masses on the scrotum. Patients are usually asymptomatic, but can have itching and white chalky discharge.¹

SCN is a form of ICC which frequently presents in childhood on the head and extremities as a solitary, hard, yellow-white papules or nodules up to 1 cm in diameter. The disorder usually occurs in children and can even be present at birth.^1–3 It has been sometimes suggested that these lesions represent calcified adnexal structures; however, in the present case, no such evidence was found on histopathology.³

SCN was initially described by Winer in 1952 and therefore also termed Winer’s nodular calcinosis.³ It is more commonly seen in males with 2:1 ratio of males to females.^2–4 Exact aetiology for this sex predilection is not well understood. However, it is a relatively rare entity especially in adults. A recent review of 109 biopsy-proven cases included only 36 adult cases.² In this study, 76% of lesions were present on the face or ears, supporting the predilection for these parts of the body.² Recently, few cases specifically affecting the periocular region have also been described.⁵

Diagnosis of SCN is confirmed by histopathology of the lesion and detailed evaluation to rule out other causes of CC. Surgical excision is the treatment of choice. Destructive methods are not recommended as they do not allow histopathological examination of the specimen.²

Learning points.

• Subepidermal calcified nodule (SCN) must be considered as a differential diagnosis in any case presenting with asymptomatic, yellowish-white plaques or nodules.

• Surgical excision followed by histopathology can be both diagnostic and therapeutic in such cases.

• Detailed biochemical and endocrinological evaluation to rule out underlying metabolic disorders and connective tissue disorders is essential before labelling the case as SCN.

Ethics statements

Patient consent for publication

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