A Collision Tumor Consisting of Granular Cell Tumor and Adenocarcinoma in the Uterus of an Aged Djungarian Hamster

Abstract

A neoplastic nodular lesion consisting of an admixture of granular cell tumor and adenocarcinoma was found in the uterus of a 26-month-old Djungarian hamster. Neoplastic cells of the uterine adenocarcinoma showed an epithelial nature in their growth patterns and by cytokeratin-immunopositive reaction, exhibiting nuclear pleomorphism. The granular cells had an abundant amount of fine granular eosinophilic cytoplasm and eccentric or central nuclei with no nuclear atypia; the granular structures were positive for periodic acid-Schiff with diastase resistance and were confirmed as lysosomes/autophagosomes by electron microscopy; immunohistochemically, the cells reacted to desmin, vimentin and α-smooth muscle actin and negatively for neurogenic, histiocyte/macrophage or epithelial markers, indicating smooth muscle origin. Because these tumors were generated from different cell origins, a diagnosis of collision tumor was made.

Mast cell and plasma cell collision tumor in the spleen of a dog

“…Although some definitions imply a diagnosis of collision tumor requires histopathology, this case provides compelling support that in some instances a collision tumor can be diagnosed cytologically. The cytology smears collected from each splenic mass showed an intimate association, and intermingling of neoplastic mast cells and plasma cells supporting that 2 distinct neoplasms coexisted in the same anatomic location; this meets the definition of collision tumor described in the majority of articles reviewed …”

“…In the majority of articles reviewed, a collision tumor is defined as the coexistence of 2 or more completely distinct cell types. independent neoplasms adjacent to each other at the same anatomic site . The coexistence often results in intermingling of cellular growth which is described as “collision” …”

“…A collision tumor should be differentiated from a composite/complex or mixed tumor, which is a tumor arising from one cell type or clone that differentiates into 2 or more distinct cell lineages (eg, canine mammary carcinoma‐complex type, canine mammary carcinoma‐mixed type) . This is important since this may have an impact on patient management/treatment.…”

“…Three case reports of collision tumors involved the skin (a hepatoid gland adenoma and a malignant melanoma; a hemangiosarcoma and a hepatoid cell/circumanal gland carcinoma; a malignant melanoma and an anaplastic sarcoma), one was associated with the testicle (a seminoma and a Sertoli cell tumor), and one was associated with the oral cavity of a dog (a squamous cell carcinoma and a malignant melanoma) were found . Case reports of collision tumors were found in a hamster, rabbit, and goat …”

“…independent neoplasms adjacent to each other at the same anatomic site. [2][3][4][5] The coexistence often results in intermingling of cellular growth which is described as "collision". 6,7 In other articles, the definition of a collision tumor is described as 2 'histologically' distinct tumor types occurring at the same anatomic site; morphologically the tumors exhibit a "side-by-side" or "one upon another" pattern implying the diagnosis of collision tumor requires histologic evaluation.…”