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Epithelial inclusion cyst arising in an intramammary lymph node: case report with cytologic findings
Masato Nakaguro1, Yasuhiko Suzuki, Shu Ichihara
1Department of Pathology, Tosei General Hospital, Seto, Aichi, Japan.
Insights
Epithelial inclusion cysts (EIC) are rare in intramammary lymph nodes. Fine-needle aspiration (FNA) cytology can diagnose these benign lesions, preventing misdiagnosis of breast cancer.
Area of Science:
- Pathology
- Cytopathology
- Surgical Pathology
Background:
- Epithelial inclusion cysts (EIC) are typically found in axillary lymph nodes.
- EIC in intramammary lymph nodes are exceptionally rare, with only one previous case reported.
- This study details a case of EIC in an intramammary lymph node in a 37-year-old woman.
Observation:
- Fine-needle aspiration (FNA) cytology revealed mature lymphocytes, squamous epithelial cells, and keratinizing material.
- The presence of squamous cells can mimic malignant breast lesions on FNA.
- Radiographic and clinical presentation can also suggest a neoplastic process.
Findings:
- The intramammary lymph node EIC demonstrated characteristic benign cytologic features.
- Differential diagnosis included squamous cell carcinoma and metaplastic carcinoma, which were ruled out.
- The lesion was confirmed as a benign epithelial inclusion cyst.
Implications:
- Awareness of intramammary lymph node EIC is crucial for accurate diagnosis.
- Correct identification prevents unnecessary surgical intervention and overtreatment for a benign condition.
- This case expands the understanding of EIC presentation in breast pathology.
Abstract:
The occurrence of epithelial inclusion cysts (EIC) in axillary lymph nodes is a rare but well recognized entity, arising either from direct implantation or from embryonal rests. Theoretically, EIC can occur in intramammary lymph nodes, but there has been only one prior report of such a lesion. Here, we describe a case of an EIC arising in an intramammary lymph node of a 37-year-old woman. This report focuses on the FNA cytologic features of this lesion and its differential diagnoses. On FNA, the EIC arising in an intramammary lymph node was characterized by mature lymphocytes, squamous epithelial cells, and keratinizing material. The presence of squamous cells can lead to the erroneous diagnosis of more common breast lesions, such as squamous cell carcinoma or metaplastic carcinoma. Contrary to these more sinister diagnoses, EIC arising in an intramammary lymph node is a benign condition. As this rare lesion sometimes mimics a neoplasm both clinically and radiographically, awareness of this entity is important to prevent over treatment.
