Chondrosarcoma-like metastasis from a poorly differentiated uterine cervical squamous cell carcinoma. A unique morphology and diagnostic pitfall in cytology.

Rare cases of metastatic squamous cell carcinoma with chondroid differentiation from esophageal primary have been reported but none from the uterine cervix. Given the rarity of this phenomenon and potential diagnostic pitfall, we present this unusual case. The patient is a 25-year-old woman who presented with shortness of breath. Computerized tomography (CT) showed several lung and pleural-based nodules. CT-guided core biopsy with touch preparations were performed on the pleural-based nodule. The touch preparations showed large, spindle-to-oval shaped cells with pleomorphic nuclei embedded in metachromatic chondroid stroma. The core biopsies also showed predominantly round-to-spindle shaped cells with hyperchromatic nuclei and prominent nucleoli embedded in a cartilaginous matrix. Her past medical history is significant for a poorly differentiated squamous cell carcinoma of the cervix, which on review showed a typical non-keratinizing squamous cell carcinoma without sarcomatous differentiation. Immunohistochemical stains performed on the pleural-based mass showed tumor positivity for AE1/AE3, CK5/6, p16, and S-100. Similar results were seen when the cervical tumor was stained retrospectively. Human papilloma virus (HPV) in situ hybridization performed on both the pleural-based mass and cervical tumor detected the presence of high-risk HPV subtypes including 16 and 18. These findings supported a lung metastasis from the prior cervical carcinoma. This case emphasizes that cervical carcinoma can develop mesenchymal (chondrosarcomatous) differentiation in metastasis even in tumors presenting with pure epithelial phenotype. Awareness of this occurrence especially on limited cytology material, knowledge of the prior history and use of ancillary tests are extremely helpful in arriving at the correct diagnosis. Diagn. Cytopathol. 2017;45:750-753. © 2017 Wiley Periodicals, Inc.