Digital carcinoma of a sweat gland metastasizing to the lacrimal gland: report of a rare case

Abstract

AbstractPurposeTo report a rare case of a digital carcinoma of the sweat gland with lacrimal gland metastasis.MethodsObservational case reportResultsA 62‐year‐old woman presented with right proptosis and diplopia. General examination showed unilateral lymphedema of the left upper limb, initially restricted to the forearm and progressively involving the upperarm with an axillary lymphadenopathy. Work‐up included a whole‐body 18F‐FDG‐PET/CT showing high uptake in the right lacrimal gland, the cervical and axillary glands. Screening for breast carcinoma was negative. A biopsy of the axillary lymph nodes was performed. Immunohistochemical analysis was positive for CK7 and negative for GATA3, ER, PR, TTF1 and SOX10. The diagnosis of a metastatic process of a CK7 positive undifferentiated tumor of unknown primary origin was withheld. Physical examination of the left upper limb showed a small scar at the level of the thumb. Retrograde investigation revealed resection of a lesion in 2016 with the histopathological diagnosis of an eccrine ductal carcinoma of a sweat gland. Immunohistochemical analysis showed concordance between primary and metastatic lesions.ConclusionAlthough the clinical presentation and the general work‐up are highly suggestive for a metastatic process in the lacrimal gland, the final diagnosis relies on the histopathology or cytology. To the best of our knowledge, metastasis of a primary cutaneous sweat gland carcinoma to the lacrimal gland has not been reported in the literature.