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Updated: Mar 26, 2026
Author Spotlight: Efficient Detection of Immune Cell-Infiltration in Cancer Tissues Using Fluorescent Immunohistochemistry
Published on: January 26, 2024
Cytokeratin-positive interstitial reticulum cell tumor: recognition of a potential "in situ" pattern
Hans Bösmüller1, Julia Klenske2, Irina Bonzheim1
1Department of Pathology, University Hospital of Tübingen, D-72076 Tübingen, Germany.
Insights
A rare Cytokeratin-positive interstitial reticulum cell (CIRC) tumor was identified in a patient with endometrial carcinoma. This accessory cell neoplasm presented as a noninvasive, circumscribed lesion in a pelvic lymph node.
Area of Science:
- Oncology
- Pathology
- Immunohistochemistry
Background:
- Cytokeratin-positive interstitial reticulum cell (CIRC) tumors are rare neoplasms derived from fibroblastic reticulum cells, originating from mesenchymal stem cells.
- These tumors are accessory cell neoplasms of lymphoid organs.
Observation:
- A case of CIRC tumor was described in a 67-year-old woman undergoing surgery for endometrial carcinoma.
- The tumor presented as neoplastic infiltrates in a pelvic lymph node, characterized by large cells with nuclear atypia, atypical mitoses, and apoptosis in a reticular pattern.
- The infiltrate was circumscribed and located in perifollicular and interfollicular areas without disrupting the lymph node architecture.
Findings:
- Immunohistochemical analysis revealed coexpression of cytokeratin and vimentin, with partial expression of CD68, CD163, and lysozyme.
- The neoplastic cells lacked markers of endometrial carcinoma, supporting the diagnosis of CIRC tumor.
- Immunostains indicated a circumscribed and noninvasive growth pattern, suggesting an early stage of CIRC tumor development.
Implications:
- This case highlights the importance of accurate diagnosis of rare neoplasms like CIRC tumors, especially in patients with other malignancies.
- The findings suggest that CIRC tumors may have an "in situ" or early noninvasive stage.
- Further research into the pathogenesis and behavior of CIRC tumors is warranted.
Abstract:
Cytokeratin-positive interstitial reticulum cell (CIRC) tumor is a very rare accessory cell neoplasm of lymphoid organs derived from fibroblastic reticulum cells, which originate from mesenchymal stem cells. We describe the histologic, immunophenotypical, and molecular features of a CIRC tumor in a 67-year-old woman who underwent hysterectomy, bilateral adnexectomy, and pelvic lymphadenectomy for endometrial carcinoma. An enlarged pelvic node contained circumscribed neoplastic infiltrates in perifollicular and interfollicular areas consisting of large cells arranged in a reticular pattern with nuclear atypia, atypical mitoses, and apoptosis, but without glandular architecture or disruption of overall architecture. The atypical infiltrate coexpressed cytokeratin and vimentin, partially CD68, CD163, and lysozyme, but lacked markers of endometrial carcinoma, consistent with a diagnosis of CIRC tumor. Despite the obviously neoplastic cytological features, immunostains revealed the circumscribed and noninvasive pattern of the lesion, possibly representing an early "in situ" stage of CIRC tumor.
