Primary lacrimal gland adenocarcinoma – First report on association with elevated serum IgG4 level: Causal or coincidence

There is a suspected association of IgG4-related orbital disease (IgG4 ROD) and malignancy. A handful of cases of such an association have been reported. This is especially of significance as IgG4 serum levels may be used as a marker of IgG4 ROD resulting in overlooking of a malignancy in such a case, especially in the absence of biopsy. Primary adenocarcinoma of the lacrimal gland is an uncommon and aggressive malignant tumor, constituting a very small subset of orbital tumors. We describe a case of a 38-year-old male who presented with a 3-month history of unilateral rapidly progressing proptosis and restricted ocular motility. Systemic workup revealed elevated serum IgG4 levels. Incision biopsy revealed features of lacrimal gland adenocarcinoma. Whole-body PET-CT excluded any other sites of involvement, thus making it a case of primary LG adenocarcinoma. The patient was advised exenteration but declined surgery and was lost to follow-up. This is the first case documenting an association between lacrimal gland adenocarcinoma with raised serum IgG4 levels. Whether this could be due an underlying lacrimal gland IgG4 ROD remains unanswered in the absence of an excision biopsy. However, this association needs to be noted for further exploration in future.