Adnexal masses

Keratoacanthoma

• Rapidly growing but spontaneously resolving tumour of the epidermis

• Can mimic an SCC

• Nodule that grows over only a few weeks

  • Elevated, “heaped” shoulder
  • Central ulcer/crater
  • Typically resolves within 2-3 months but can leave a scar

• Histologically

  • Central mass of keratin (pink with H&E stain)
  • Hyperplastic epidermis with clear demarcation between this raised edge and normal skin surface
  • Demonstrate hyperkeratosis (of the epidermis) and sometimes also dyskeratosis (keratinisation within the dermis)

Epidermoid cyst

• Demonstrate dyskeratosis (purely)
• Histologically: keratin-filled cavity within the dermis lined by keratinised stratified squamous epithelium

Basal cell carcinoma

• >90% of malignant eye tumours

• Caucasians over 50 years old

• Associated with:

  • Sunlight exposure
  • Gorlin-Goltz syndrome (aka basal cell naevus syndrome). Autosomal dominant mutation of PTCH gene on 9q
  • Xeroderma pigmentosa: autosomal recessive, extreme sensitivity to UV light
  • Albinism: usually autosomal recessive (lack of melanin)
  • Bazex syndrome: X-linked dominant disorder of hair follicles
  • Male gender
  • Arsenic exposure
  • Immunosuppression
  • Fair skin/caucasian
  • Smoking

• Appearance

  • Nodular (or solid)
  • Central ulcer
  • Rolled edge
  • Morphoeic type: scirrhous (hard/fibrous) plaque resembling scar
  • Occasionally pigmented

• Medial canthus is most common location (48%) followed by lower eyelid, upper lid and lateral canthus (least common)

  • Medial canthal BCC tends to be more aggressive and more likely to be deeply invasive

• Management: surgical excision
  • Superficial BCCs can be treated with imiquimod: an immune response modulator that stimulates apoptosis in BCC cells. Clearance rate of 82-90%
  • Cure rates approach 95% ie 5% recurrence rate depending on treatment and histological subtype
  • Metastasis occurs on 0.1% typically lungs and bone
  • There is a 35% risk of BCCs in other sites

Squamous cell carcinoma

• 1-5% of eyelid cancers

• Associated with:

  • Sunlight exposure
  • Immunosuppression

• Appearance:

  • Fast growing
  • Nodular ulcer
  • Papillomatous growth
  • May have overlying keratinous horn

• Disseminates via lymphatics: preauricular nodes (upper lid) and submandibular nodes (lower lid)

• Histology:

  • Well-differentiated: pink cytoplasm, intercellular bridge, keratin pearls
  • Spindle cell morphology rare: more aggressive

• Can affect the cornea and conjunctiva with identical histology. Associated with AIDS

Sebaceous cell carcinoma

• <1% of eyelid tumours

• Can mimic benign inflammatory and malignant processes

• Typically arises from meibomian glands or glands of Zeis

• More common in upper lid

• Risk factors -Age (elderly)

  • Female
  • Muir-torre syndrome: sebaceous neoplasm-visceral carcinoma. Loss of mismatch repair genes hMSH2 and hMLH1. Poor prognosis.

• Features

  • Nodule: firm nodule resembling a chalazion (always suspect in recurrent chalazion)
  • Spreading: diffuse infiltration resembling chronic blepharoconjunctivitis +/- loss of lashes
  • May mimic chalazion, SCC and BCC

• Histology:

  • Nodular: lobules of tumour cells with foamy/vacuolated cytoplasm
  • Diffuse: individual cells invading epithelium (Pagetoid spread)
  • Variable differentiation
  • Oil red O stains the fat within malignant cells red

• >6 months delay to diagnosis significantly worsens mortality

• Lymph node metastasis affects 8-28%

• Pagetoid spread: consider mapping biopsies of the conjunctiva

• Management may involve parotidectomy as frequently spreads here as well as wide local excision, lymph node clearance +/- exenteration

Merkel cell carcinoma of the eyelid

• Very rare

• Neuroendocrine malignancy

• Commoner in elderly patients

• Rapid aggressive growth

• Clinical features

  • Non-tender purple nodule (violaceous red colour)
  • Fusiform shape
  • Palpable lymph nodes
  • Overlying telangiectasia

• Poor systemic prognosis

• Consider orbital MRI to exclude orbital invasion

• Immunohistochemical staining with neuron specific enolase is a hallmark. Otherwise histology shows highly undifferentiated tumour

Naevi

• Begin junctional, become compound then later, intradermal
  • Junctional: within epidermis. Flattest, darkest, highest malignant potential
  • Compound: span epidermis and dermis. Slightly elevated, moderately pigmented, intermediate malignant potential
  • Intradermal: within dermis. Most elevated, least hyperpigmentation and lowest malignant potential