A Case of Axillary Tail of Spence Carcinoma or Occult Breast Carcinoma?- A Diagnostic Dilemma

Introduction: Carcinoma of the axillary tail of Spence (CATS) is rare with an incidence of 0.1-2%. It is a type of breast cancer that develops at a specific anatomical position in the breast and often under-diagnosed.

Case Presentation: A 37 year-old lady presented with an axillary swelling for 2 months. Clinically, an axillary lump was palpable and an ultrasound confirmed a 1cm axillary node. Excision of this node revealed metastatic carcinoma with breast as the primary, ER/PR positive, HER-2 negative. Mammogram and MRI performed showed no suspicious breast lesions. CT TAP confirms no distant metastasis. Excision of the previous scar tissue revealed non-sizeable invasive carcinoma, with deep margins involved. Axillary dissection showed 5/13 positive lymph nodes, pT0N2a. Re-excision of the deep margins revealed invasive carcinoma with 3mm foci of invasion. The final pathological staging was pT1a N2a M0 and adjuvant chemoradiotherapy was commenced.

Discussion: Careful evaluation is necessary to differentiate CATS from other diagnoses such as occult carcinoma, lymphoma or non-breast metastatic lymphadenopathy. In our case, the initial diagnosis of occult carcinoma was a possibility, and the pathology of CATS was proven much later despite an MRI performed. This diagnostic dilemma is faced by surgeons, radiologists, pathologists and oncologists, especially in a setting where resources are limited. Prompt diagnosis is important as prognosis is proven to be worse than cancers in other locations of the breast.

Conclusion: When dealing with patients with an axillary swelling, it is crucial to keep the diagnosis of CATS in mind.