A ‘recurrent chalazion’ that will not resolve

Sebaceous carcinoma of the right upper eyelid with pagetoid intraepithelial spread — Mohs micrographic excision and tarsoconjunctival flap reconstruction; Muir-Torre evaluation arranged

Learning points

• Sebaceous carcinoma of the eyelid is the great chalazion mimic. Any 'recurrent' or non-resolving chalazion in an older patient (particularly > 60), or any persistent unilateral blepharitis, warrants biopsy.
• The upper eyelid is the commonest site (greater meibomian gland density). Other clues: madarosis (loss of eyelashes), unilateral conjunctival injection, yellowish nodularity within the tarsal plate.
• Pagetoid intraepithelial spread is characteristic and is one reason for the high local recurrence rate — tumour cells track through the conjunctival and skin epithelium well beyond the clinically apparent mass.
• Map biopsies of the conjunctival epithelium are recommended to define the extent of pagetoid spread before definitive excision.
• Definitive treatment is wide excision with margin control — Mohs micrographic surgery or formal frozen-section-controlled excision — followed by oculoplastic reconstruction. Periocular subunit principles apply (Hughes tarsoconjunctival flap, Cutler-Beard, Mustardé cheek rotation).
• Regional nodal metastasis can occur (preauricular, submandibular, cervical) — clinical and radiological assessment of the regional basin is part of staging. SLNB is increasingly considered for higher-risk disease but is not standard UK practice.
• Muir-Torre syndrome — an autosomal dominant variant of Lynch syndrome (mismatch repair gene mutation, most commonly MSH2 or MLH1) with sebaceous neoplasms plus visceral malignancies (especially colorectal, urothelial, endometrial). All sebaceous carcinomas should be screened with MMR immunohistochemistry; refer to clinical genetics if MMR-deficient.