# Isolated Axillary Lymphadenopathy Presenting as Carcinoma of Unknown Primary in a Female Patient: A Diagnostic and Therapeutic Challenge

## TL;DR

A 47-year-old woman presented with isolated axillary lymph node cancer of unknown origin, highlighting the challenges in diagnosing and treating such rare cases.

## Contribution

This case report emphasizes the diagnostic and therapeutic challenges of CUP presenting as isolated axillary lymphadenopathy and the role of multidisciplinary approaches.

## Key findings

- The patient had a hypermetabolic axillary mass with no identifiable primary tumor.
- Immunohistochemistry showed markers consistent with metastatic carcinoma.
- The patient had a normal follow-up PET-CT after surgery, suggesting a potentially better prognosis.

## Abstract

Carcinoma of unknown primary (CUP) is a distinct and uncommon clinical entity characterized by metastatic disease without an identifiable primary tumor, despite thorough investigation. Isolated axillary lymphadenopathy as the sole manifestation is rare and diagnostically challenging, particularly in younger women. The patient was a 47-year-old woman with painless right axillary swelling with no breast or systemic lesions. Fine-needle aspiration cytology (FNAC) suggested metastatic carcinoma. PET-CT showed a hypermetabolic right axillary mass without evidence of disease elsewhere. Excisional biopsy confirmed poorly differentiated carcinoma; immunohistochemistry (IHC) was positive for PanCK, CK7, TRPS1, and PAX8 with a high Ki-67 index (70%). A multidisciplinary decision led to axillary lymph node dissection, which revealed no residual metastatic disease. The follow-up PET-CT was normal. This case highlights the importance of a thorough diagnostic approach. IHC, advanced imaging, and multidisciplinary input are critical for diagnosis and management. CUP localized to lymph nodes may have a more favorable prognosis.