Sebaceous gland carcinoma SGC

SGCs are very rare, with a predilection for the periocular area. In addition, SGC of the eyelids has a tendency to produce widespread metastes whereas such tumours occurring elsewhere on the skin rarely metastasize. SGC occurs with increasing frequency with advancing age. The tumour has a predilection for the upper eyelid, but diffuse upper and lower eyelid involvement may occur in patients presenting with chronic blepharoconjunctivitis.

This tumour is well recognised for its ability to masquerade as chronic blepharo-conjunctivitis or recurrent chalazion (masquerade syndrome). Recurrent chalazion or atypical solid chalazions should alert the ophthalmologist to the possibility of underlying sebaceous gland carcinoma (Figure 6.6). Histopathologic features of sebaceous gland carcinoma are characteristic and may be confirmed by lipid stains (oil red O) on fresh tissue specimens. Multicentric origin is a feature of some SGCs. Clinical presentation of chronic

Sebaceous Gland Carcinoma

Figure 6.6 Sebaceous gland carcinoma: (a) external appearance, (b) following lid eversion.

Figure 6.6 Sebaceous gland carcinoma: (a) external appearance, (b) following lid eversion.

Figure 6.5 Squamous cell carcinoma. 48

blepharoconjunctivitis has been correlated with the pathologic features of Pagetoid involvement of the surface epithelium.

Despite the characteristic features, the tumour is frequently misdiagnosed. The aggressive behaviour and significant morbidity and mortality associated with SGCs have traditionally been attributed to the misdiagnosed tumours. The 5 year survival is 30-40%. It is clear that early diagnosis and appropriate therapy significantly reduce the long-term morbidity associated with this tumour.

Clinical features include

• Affects females more commonly than males

• More common in orientals

• Tends to occur in older patients

• Has a predilection for the upper eyelid

• Arises most commonly from the meibomian glands

• Has a lesser tendency to ulcerate

• Masquerades as recurrent chalazion or chronic blepharoconjunctivitis (Masquerade syndrome)

• May metastasize prior to establishing correct diagnosis

• High incidence of metastases

• Difficult delineation of tumour margins due to intraeithelial Pagetoid spread and/or multicentric pattern

• May be misdiagnosed histologically especially if lipid stains are not used on properly prepared tissue.

Poor prognostic factors include

• Invasion - vascular, lymphatic, or orbital

• Diffuse involvement of both eyelids

• Multicentric origin

• Symptoms present > 6 months

Note:

• In the Pagetoid pattern there is often involvement of both eyelids as well as the conjunctiva.

• Approximately 30% of sebaceous gland carcinomas recur.

• Systemic extension occurs by contiguous growth, lymphatic spread, and haematogenous seeding.

• The tumour spreads mainly to the orbit, the preauricular/submandibular nodes or parotid gland - less frequently to the cervical nodes, lung, pleura, liver, brain and skull.

• Some patients remain alive and well for long periods with regional node involvement -radical neck dissection for isolated cervical node disease is often indicated.

• Mortality is approximately 20-30% mainly due to late diagnosis.

Diagnosis:

A high index of suspicion is required.

• Shave biopsy - may only show inflammation

• Full thickness eyelid biopsy is required

• Random conjunctival biopsies

• Fat stains - alert the pathologist

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