A 53-year-old woman presented with a left painless enlarging lacrimal fossa lesion with hypoglobus and choroidal folds. 18 months earlier, she had undergone surgery and chemoradiotherapy for right maxillary sinus adenoid cystic carcinoma. After initial 1.5T magnetic resonance imaging, a double primary of left lacrimal gland adenoid cystic carcinoma with tricompartmental (frontal bone, lacrimal and temporalis fossa) involvement was suspected. However, subsequent high-field multiparametric 3T magnetic resonance imaging suggested a solitary metastasis with a subperiosteal location and an uninvolved lacrimal gland. The solitary metastasis was confirmed intraoperatively and pathologically. CASE REPORT HKJOphthalmolVol.25 No.1 lacrimal fossa lesion within a short period together with invasion to the surrounding frontal bone and temporalis fossa was highly suggestive of malignancy. However, on high-field 3T MRI, the subperiosteal location and the normal lacrimal gland concluded that the diagnosis of an advanced primary lacrimal gland ACC was unlikely.Only one case of metachronous primary ACC has been reported; the patient had a history of an index maxillary sinus ACC with esophageal carcinoma 14 years later. 6 Whereas there have been 12 cases of lacrimal gland or maxillary sinus ACC with metastasis to other organs including liver, kidneys, and lungs. [7][8][9][10][11][12][13][14][15][16] Therefore, primary versus metachronous ACC are differential diagnoses. High-field multiparametric MRI is an important tool to assess orbital masses.