Signet Ring Epithelioid Stromal Tumor of the Small Intestine

Abstract

Cells having a signet ring appearance can occur in mesenchymal, lymphoid, and other nonepithelial neoplasms. We report the case of an intestinal stromal tumor with smooth muscle differentiation and a prominent signet ring cell component. The presence of signet ring forms of smooth muscle cells in sections of paraffin-embedded tissue often contrasts with a lack of cytoplasmic spaces by electron microscopy, and the ultrastructural finding of signet ring-like areas in the present case can be attributed to the fact that the tissue for electron microscopy was retrieved from paraffin blocks where this peculiar artifact already existed. Ultrastructural examination of the signet ring-like areas suggests that they originated as retraction spaces which may have resulted from variations in intracellular tension forces related to the distribution of actin filaments.

Collecting-Duct Carcinoma of the Kidney with Prominent Signet Ring Cell Features

“…One possible cause is artifact. Signet ring-like changes attributable to biopsy and formalin fixation have been found in lymphocytes and smooth muscle cells in transurethral resection specimens of the prostate, gastric lymphoma, and gastrointestinal stromal tumor (25)(26)(27). We cannot completely rule out the possibility of retraction artifact in our case because tissue sections taken for both histological and ultrastructural studies were formalin fixed.…”

Signet ring cells of stromal derivation in the uterine cervix secondary to cauterisation: report of a previously undescribed phenomenon

“…There are also examples of non-epithelial tumours with a signet ring morphology; signet ring cells are occasionally seen in adenomatoid tumours and in benign ovarian neoplasms such as sclerosing stromal tumour and fibroma10 – 13 and the rare signet ring–stromal tumour of the ovary is entirely composed of such cells. Similar signet ring-stromal tumours or stromal nodules with signet ring cells have been described in other organs such as the prostate, small intestine and testis 14 – 16. Signet ring variants of lymphoma and malignant melanoma have been reported 17 18.…”

Gastrointestinal Stromal Tumor with Structures Resembling Intracytoplasmic Lumina

“…Without cytokeratin staining especially we cannot confirm these structures as ultrastructural markers of true glandular epithelial differentiation. Although they do bear a resemblance to epithelial lumina, they may represent either a primitively developed luminal structure in cells insufficiently differentiated to have elaborated true epithelial proteins (cytokeratin), or a degenerated structure [30]. Although uncommon and as yet of uncertain significance, these structures merit attention in order to understand them and the tumors in which they occur more thoroughly.…”