A Rapidly Enlarging Squamous Inclusion Cyst in an Axillary Lymph Node following Core Needle Biopsy

Abstract EN

A 73-year-old woman was found to have a 1.7 cm axillary mass, for which a core needle biopsy was performed.

The specimen revealed fragmented squamous epithelium surrounded by lymphoid tissue consistent with a squamous inclusion cyst in a lymph node, but a metastatic squamous cell carcinoma could not be excluded.

Within one month, the lesion enlarged to 5 cm and was excised.

Touch preparation cytology during intraoperative consultation displayed numerous single and sheets of atypical epithelioid cells with enlarged nuclei and occasional mitoses, suggesting a carcinoma.

However, multinucleated giant cells and neutrophils in the background indicated reactive changes.

We interpreted the touch preparation as atypical and recommended conservative surgical management.

Permanent sections revealed a ruptured squamous inclusion cyst in a lymph node with extensive reactive changes.

Retrospectively, the atypical epithelioid cells on touch preparation corresponded to reactive histiocytes.

This is the first case report of a rapidly enlarging ruptured squamous inclusion cyst in an axillary lymph node following core needle biopsy.

Our case demonstrates the diagnostic challenges related to a ruptured squamous inclusion cyst and serves to inform the readers to consider this lesion in the differential diagnosis for similar situations.