Fine needle aspiration biopsy of splenic hamartoma with bizarre stromal cells: a case report

Splenic hamartoma with bizarre stromal cells: a case report and literature review

Background

Splenic hamartoma is a rare benign vascular proliferative lesion composed of unorganized sinusoid-like channels lined with plump or flat endothelial cells and characterized by a CD8-positive immunophenotype of the lining cells. Scattered bizarre stromal cells can be found in some splenic hamartomas. The presence of splenic hamartoma with bizarre stromal cells is extremely rare and these bizarre cells make it possible to be regarded as a malignancy. Recognition of this rare histologic variant will help to avoid diagnostic confusion and overtreatment of this benign entity.

Case presentation

We report a case of a 40-year-old man with occasional left-sided waist back pain. A splenic space-occupying lesion was detected by ultrasound and magnetic resonance imaging. Microscopically bizarre large cells were scattered throughout the splenic hamartoma. The cells exhibited atypical nuclei, scarcely visible cytoplasm, and vesicular chromatin, and they did not form expansile clusters and lacked mitotic activity. An immunohistochemical panel was performed. The bizarre cells strongly expressed vimentin, and the Ki-67 index was very low. The lesion was diagnosed as a splenic hamartoma with bizarre stromal cells.

Conclusions

To the best of our knowledge, this is the first systematic review on a splenic hamartoma with bizarre stromal cells; only six cases have been described in the literature. Proper identification is important to secure adequate treatment.

[Inflammatory esophageal polyp with bizarre stromal cells: possible diagnostic pitfall]

In the gastrointestinal tract an accurate diagnosis of tumor-like lesions can be challenging. In patients with reflux disease regenerative hyperplasia of esophageal squamous epithelium may show marked pleomorphism and atypia thereby simulating malignancy. Bizarre stromal cells are another diagnostic pitfall. We present the case of a 46-year-old patient with symptoms of reflux disease who was diagnosed with a benign inflammatory polyp at the distal end of the esophagus. Histology revealed bizarre cells within the stroma of the polyp characterized by nuclear hyperchromatism and enlargement. Mitoses were not observed. The atypical cells were positive for vimentin. The Ki67/MIB-1 proliferation rate was low. The morphology and etiology of bizarre stromal cells, including helpful features for differential diagnosis are thoroughly discussed.

Endoscopic ultrasound guided fine-needle aspiration of a splenic hemangioma with extramedullary hematopoiesis

Extramedullary hematopoiesis (EMH) is the production of mature blood elements outside of the bone marrow and can occur as a compensatory result of a marrow replacing process or from marrow space occupying lesions such as tumor or marrow fibrosis. EMH can also be induced by factors elicited by neoplasms, such as vascular endothelial growth factor (VEGF). Usually, EMH is a diffuse process most commonly observed in lymph nodes, liver, and spleen. Rarely, EMH can form a mass lesion. Although the spleen is a common site for diffuse EMH, it is a rare location for a mass forming EMH. Hemangiomas are the most common benign tumors of the spleen. A case of a discrete, 8 cm lesion was noted incidentally on CT scan in a 59-year-old man with no significant past medical history. Endoscopic ultrasound guided fine-needle aspiration (EUS FNA) biopsy was performed and cytologic examination revealed trilinear hematopoiesis, with the most distinctive elements being megakaryocytes and erythroid precursors. A diagnosis of EMH was made. On resection, the mass was a hemangioma with EMH. EUS guided FNA is a useful tool for diagnosing splenic masses. Awareness of EMH, both as a mass forming lesion and a feature associated with benign and malignant vascular lesions is important, especially in patients with hematologic malignancies or marrow replacing processes.