Chronic bilateral dacryo-adenitis in identical twins: a possible incomplete form of Sjögren syndrome

We report an unusual case of chronic bilateral dacryo-adenitis in 10-year-old identical twin sisters. Both girls presented with bilateral lacrimal gland enlargement and developed moderate xerophthalmia and keratitis. Both the lacrimal and minor salivary gland biopsies showed a non-granulomatous inflammatory infiltration of mononuclear cells. All granulomatous diseases and neoplasms could therefore be ruled out and only Sjögren syndrome and very few other forms of chronic dacryo-adenitis remained as possible diagnoses. Both patients and their parents were evaluated for auto-antibodies. Very low titres of smooth muscle antibodies were found in one, antinuclear antibodies in two and anti-dsDNA antibodies in all four members of the family. Even though the titres of antinuclear and anti-dsDNA antibodies increased in one of the sisters, both patients did not develop any sign or symptom of a systemic connective tissue disease. During the 6 years' follow up, both patients showed persistent tarsal gland enlargement but no other symptoms apart from a moderate xerophthalmia and occasional mild keratitis.