A Rare Occurrence of Right Axillary Tubular Apocrine Adenoma: A Case Report from South-South Nigeria

Introduction: Tubular apocrine adenoma (TAA) is an extremely rare benign tumour of the skin adnexa/appendage – the sweat gland. Just less than 150 cases have been reported worldwide in the medical literature since the condition was first described. Most of this type of tumours are found on the scalp. This case highlights the occurrence of this tumour in the axilla, which may often be mistaken for axillary lymphadenopathy secondary to breast lesions/conditions.Case presentation: A 36-year-old multiparous woman who presented in the gynaecology clinic with a 2-year history of a painless right armpit seed-like swelling, she had no axillary breast tissue. Mammography and high resolution breast sonogram done had essentially normal breast findings. A diagnosis of right axillary subcutaneous granuloma, to rule out secondary tumour from an occult breast lesion/tumour was made, and she was counselled for excision biopsy. Preoperative assessment was done with physical examination and investigations. Following excision biopsy, histopathological assessment revealed overall features of tubular apocrine adenoma. Her post-operative course and subsequent follow-up has been uneventful.Conclusion: axillary tubular apocrine adenoma is a distant rarity, however, a high index of suspicion may be required when a woman presents with a subcutaneous axillary lump. The excision biopsy of the axillary lump should be subjected to histopathologic assessment with or without immunohistochemistry, to be able to clinch the diagnosis of tubular apocrine adenoma.