Epidermal cyst with calcifications

Case contribution: Dr Radhiana Hassan


  • A 61 years old male with underlying scleroderma under Rheumatologist follow-up
  • Presented with progressive swelling over right thumb for 4 years
  • Increase in size
  • No limitation of movement but patient had intermittent pain
  • No clumsiness of hand
  • Clinical examination shows a multilobulated swelling over pulp of thumb 2×2 cm, swelling thetered to skin but non-tender.
  • Patient is able to flex IPJ and MCPJ. Distal perfusion is good.

Plain radiograph findings:

  • Soft tissue thickening at pulp of right thumb
  • Multiple foci of dense calcifications are seen within this thickened soft tissue
  • No obvious erosion or periosteal reaction of adjacent phalanges.
  • Visualized joints are also normal.

Intra-operative findings:

  • One partially liquified lesion over radial side of tip of right thumb excised to its base
  • Another hard whitish deposits over ulnar side was also removed

HPE findings:

  • Macroscopy: specimen labelled as tumour calcinosis consists of a piece of whitish piece of tissue.
  • Microscopy: sections show a cystic lesion lined by a keratinized stratified squamous epithelium. The cavity of the cyst is filled with lamellated keratin flakes. Negative for malignancy.
  • Interpretation: Epidermal cyst

Diagnosis: Epidermal inclusion cyst with intralesional calcifications.


  • Epidermal inclusion cysts are the most common cutaneous cysts.
  • Synonyms include: epidermoid cyst, epidermal cyst, infundibular cyst, inclusion cyst and keratin cyst
  • Epidermoids are slow-growing benign cysts bounded by a wall of stratified squamous epithelium
  • Epidermoid cyst can occur anywhere in the body bur commonly seen in the scalp, face, neck, trunk and back.
  • Less than 10% occur in the extremities
  • The size ranges from a few mm to a few cm
  • Lesion may remain stable or progressively enlarge over time. No reliable predictive feature to tell if an epidermal inclusion cyst tend to be larger, erythematous or more noticeable to patient
  • They do not originate from sebaceous gland, thus are not sebaceous cyst
  • Majority are sporadic and not contagious, it can also resolve on their own
  • Imaging findings reflects the content of the lesion – debris, water, cholesterol and keratin
  • Typically unruptured epidermoid cysts are well-defined round or oval-shaped lesion of high signal intensity on T2WI. However variable signal intensity also reported depending on presence of keratin debri or calcification.
  • Malignant degeneration of epidermal cyst is uncommon. Squamous cell carcinoma is seen in 2.2% of cases
Author: radhianahassan