SMARCB1/INI1-deficient pancreatic undifferentiated rhabdoid carcinoma mimicking solid pseudopapillary neoplasm: A case report and review of the literature.

BACKGROUND: SMARCB1/INI1-deficient pancreatic undifferentiated rhabdoid carcinoma is a very aggressive tumor that is rarely reported in the literature. The tumor has a predominant rhabdoid cell component and different patterns of growth have been reported. CASE SUMMARY: A 59-year-old woman presented with diffuse abdominal pain, increasing in severity and accompanied by weight loss, nausea, and vomiting. Imaging showed a pancreatic head mass. Fine needle aspiration demonstrated atypical epithelioid cells with a pseudopapillary growth pattern suggestive of solid pseudopapillary neoplasm. The excised neoplasm showed monotonous epithelioid and focally spindle cells with pseudopapillary structures, rhabdoid features, and loss of SMARCB1 protein expression with wild-type KRAS, consistent with a SMARCB1/INI1-deficient undifferentiated rhabdoid carcinoma. The patient's condition deteriorated rapidly following surgery and she expired 3 mo post operation. CONCLUSION: In this article, we report the first case of SMARCB1/INI1-deficient undifferentiated pancreatic rhabdoid carcinoma mimicking solid pseudopapillary neoplasm.

Two Cases of Spindle Cell Neoplasms in Patients Undergoing Holmium Laser Enucleation of the Prostate.

Background: Holmium laser enucleation of the prostate (HoLEP) has proven to be effective in benign proliferations of the prostate resulting in large prostatic volumes. It is a less-invasive surgical alternative to transurethral resection and surgical resection. Prostatic adenocarcinoma can incidentally be found in the enucleated tissue. Occasionally, nonadenocarcinomatous forms of neoplasia occur such as sarcoma. Case Presentation: Two male patients, both 65 years old, undergo HoLEP for gigantic prostates. The first patient presented with recurrent hematuria and clot retention. After HoLEP, the patient voiding symptoms improved. Pathologic immunostaining of the tissue showed spindle cell proliferation consistent with stromal tumor of uncertain malignant potential (STUMP). The second patient presented with acute urinary retention and subsequently underwent HoLEP. Pathologic examination of the enucleated tissue was consistent with prostatic stromal sarcoma. Conclusion: HoLEP is a well-established surgical treatment for gigantic proliferations of benign prostatic tissue. Occasionally, patients who are candidates for HoLEP may have a rare underlying pathologic condition such as a sarcoma or a STUMP. Exclusion of underlying malignant processes in massive prostates is necessary before operating.