Malignant Transformation of Giant Cell Tumor of Bone 7 years After Initial Surgery: A Case Report and Literature Review.

CASE: A 64-year-old man with a history of giant cell tumor of bone (GCTB) in the fibula 7 years earlier developed a recurrence with histologic features of osteosarcoma. Both the primary GCTB and the secondary osteosarcoma were found to have the H3F3A gene mutation. Despite immediate above-the-knee amputation, the patient died of respiratory failure because of lung metastases 3 months later. CONCLUSION: This is the first report of proven H3F3A mutation in both the primary GCTB and the secondary osteosarcoma in the same case. Clinicians should consider secondary malignancy in patients presenting with a lesion at the site of a previously treated GCTB after a long interval.

Desmoplastic Fibroblastoma Invading the Humerus.

Desmoplastic fibroblastoma (DFB) is an uncommon, benign, soft tissue tumor. The tumor most often presents as a slowly growing, painless soft tissue mass and is usually small. There have been only a few reports of patients with DFB who presented with bone invasion. Herein, we report the case of a 66-year-old woman with DFB with bone invasion in her left axilla. A lump under the left axilla was detected and was associated with pain and limited range of motion (ROM) of the shoulder. Computed tomography showed a soft tissue mass with invasion of the adjacent left humerus. Magnetic resonance imaging revealed a lesion with low signal intensity on T1- and T2-weighted images, and weak internal enhancement on postcontrast T1-weighted images with fat suppression. Histologic evaluation of a preoperative needle biopsy revealed DFB with FOSL1 expression. The tumor was marginally excised. Postoperative outpatient follow-up demonstrated a significant improvement in pain and ROM of the shoulder and no recurrence after 1 year. Even though DFB with bone invasion can cause pronounced clinical symptoms with pain and limited ROM, we conclude that simple excision is an adequate treatment.

Primary retroperitoneal mucinous cystadenocarcinoma with transition from the mesothelium.

INTRODUCTION: Mucinous cystic neoplasms are uncommon among the tumors that develop in the retroperitoneum. We report a case of primary retroperitoneal mucinous cystadenocarcinoma with pathological considerations. CASE PRESENTATION: A 47-year-old woman complaining of abdominal discomfort presented at our hospital. Abdominal computed tomography and magnetic resonance imaging showed a large cystic tumor with small solid nodules located in the right retroperitoneum. The tumor was completely removed and the microscopic findings were consistent with primary retroperitoneal mucinous cystadenocarcinoma. Two years after the surgery, the patient is alive without recurrence of the tumor. CONCLUSION: The microscopic findings suggested that the primary retroperitoneal mucinous cystadenocarcinoma developed from the metaplasia of the remnant coelomic epithelium. A complete tumor resection that includes the adjacent peritoneum is important to prevent local recurrence.

MUC4 expression in meningiomas: under-recognized immunophenotype particularly in meningothelial and angiomatous subtypes.

AIMS: MUC4 is a transmembrane glycoprotein that plays a role in cell growth signalling and is expressed in various epithelial tissues. Gene expression profiling and immunohistochemical analyses revealed that MUC4 is also constantly and specifically expressed in low-grade fibromyxoid sarcomas and sclerosing epithelioid fibrosarcomas among the mesenchymal tumours, and immunohistochemical detection of MUC4 is extremely useful for their diagnoses. In our routine pathological practice, we noticed that meningiomas are also often positive for MUC4, which has not yet been reported previously, despite the extensive scrutiny of its expression in soft tissue tumours. METHODS AND RESULTS: We examined immunohistochemically the expression of MUC4, progesterone receptor (PgR) and somatostatin receptor 2A (SSTR2A) in 140 meningiomas of various histological subtypes and 123 other mesenchymal tumours, including intracranial or sinonasal tumours and peripheral nerve sheath tumours. MUC4 was expressed in 130 meningiomas (92.9%). MUC4 expression was constant and almost diffuse in meningothelial and angiomatous subtypes, whereas it was limited in 5% or fewer tumour cells or absent in 26 of 28 fibrous meningiomas. All other mesenchymal tumours examined were negative for MUC4. PgR and SSTR2A were expressed in 94 (67.1%) and 134 (95.7%) meningiomas, respectively. Five of six SSTR2A-negative meningiomas focally expressed MUC4. CONCLUSIONS: MUC4 is expressed variably but almost consistently in meningiomas, particularly in meningothelial or angiomatous subtypes. Its immunohistochemical detection is useful to distinguish meningiomas from other intracranial or head and neck mesenchymal tumours, particularly those with epithelioid features. Our study could expand a variety of MUC4-positive mesenchymal tumours.

Retroperitoneal dedifferentiated liposarcoma with huge cystic degeneration: A case report.

Prominent cyst formation is an unusual feature of liposarcoma. We report here a case of dedifferentiated liposarcoma with huge cystic change without preoperative chemo- or radiation therapy. The lesion arose in the retroperitoneum juxtaposed to the right kidney of a 67-year-old woman. She underwent a surgical removal of the retroperitoneal cyst. The cystic tumor contained 1600 mL of old bloody fluid, and its wall was composed of edematous, inflamed or sclerosing fibrous tissue with fatty tissue containing abundant atypical stromal cells, which were immunohistochemically positive for MDM2 and CDK4, and demonstrated MDM2 gene amplification by fluorescence in situ hybridization. The wall was contiguous to an atypical lipomatous nodule located in the mesentery. The following surgical specimens of the right hemicolectomy and right nephrectomy revealed atypical cells infiltrating into the subserosa of the colon and the perirenal fat tissue or that in the renal sinus. This case indicates that well differentiated or dedifferentiated liposarcoma should be also considered as a differential diagnosis of perirenal cystic mass.