Carcinoma of the axillary tail of Spence: A rare case report

Carcinoma arising from the axillary tail of Spence (CATS) is a rare entity that requires a high level of clinical suspicion. The clinicopathologic, prognostic, and imaging features of CATS are poorly understood.

A 46-year-old woman presented to our hospital with right axillary swelling associated with bleeding and foul-smelling discharge. She had initially presented to a different hospital with a similar presentation where she was diagnosed with metastatic carcinoma, favouring adenocarcinoma on the FNAC report, following which she received 3 cycles of chemotherapy. MRI and PET-CT scan workups at our hospital showed a soft tissue mass likely arising from the axillary tail of the right breast with a few enlarged axillary lymph nodes and an unremarkable right breast. She underwent excision of the mass with axillary lymph node dissection and reconstruction with a pedicled Latissimus dorsi flap. The final diagnosis was based on immunohistochemistry, with tumor cells positive for GATA3 and CK-7, negative for estrogen and progesterone receptors (ER, PR), positive for human epidermal growth factor receptor 2 (Her2 neu), and having a Ki-67 labelling index of 45 %.

Carcinoma of the axillary tail of Spence (CATS) has a reported incidence of 0.3 %. There have been only few papers till date that have reported the clinicopathologic, prognostic, and imaging features of CATS. MRI is an important imaging modality to localize CATS. Histologic examination aids in the diagnosis by identifying the presence of a histologic pattern of primary breast carcinoma and immunohistochemical characteristics such as ER, PR, Her2neu, and gross cystic disease fluid protein (GCDFP). Due to the rarity of CATS, no specific guidelines concerning management currently exist. Surgical management involves wide local excision of the axillary mass with axillary lymph node dissection.

CATS, even though rare, should be considered in the differential diagnosis of a patient presenting with an axillary mass. MRI is a valuable tool to distinguish CATS from other lesions. Immunohistochemistry is essential to confirm the diagnosis.