Expression of CD99 in Multiple Myeloma: A Clinicopathologic and Immunohistochemical Study of 170 Cases

BACKGROUND: Multiple myeloma (MM) is a heterogeneous and ultimately fatal disease. Risk stratification using prognostic biomarkers is crucial to individualize treatments. We sought to investigate the role of CD99, a transmembrane protein highly expressed in many hematopoietic cells including subpopulations of normal and neoplastic plasma cells, for MM risk stratification. METHODS: CD99 expression was measured in paraffin samples of bone marrow and extramedullary biopsies of 170 patients with MM. Patients were divided into those with high score (moderately and strongly positive) and low score (negative and weakly positive), with all staining being cytoplasmic and/or membranous. RESULTS: High anti-CD99 immunostaining was observed in 72 of 136 (52.9%) bone marrow biopsies and 24 of 87 (27.6%) extramedullary biopsies in MM. High CD99 expression of extramedullary specimens was associated with significantly longer overall survival (OS; p=.016). High CD99 expression of extramedullary specimens was also associated with better prognosis in the nonautologous stem cell transplantation group of MM patients (p=.044). In multivariate analysis, International Staging System stage was an independent prognostic factor, whereas CD99 expression was no longer statistically significant. CONCLUSIONS: Expression of CD99 in extramedullary specimens was correlated with longer OS, suggesting that CD99 may be a helpful immunohistochemical marker for risk stratification.

Primary Hepatic Neuroblastoma: A Case Report

Neuroblastoma is a malignant tumor of primordial neural crest origin. It usually develops along the sympathetic nervous system, such as the adrenal glands or paramedian sympathetic chain and metastasizes to the liver most frequently. However, a primary hepatic neuroblastoma has not been reported yet. Here, we report a case of 29-year-old woman who presented with a solitary hepatic mass. Grossly, the mass was large, creamy, rubbery firm, and showed focal hemorrhage and central cavitation. Microscopically, the tumor cells were arranged in small nests of spindle to ovoid cells with abundant neuropil. The neuroblastic nature of the tumor was confirmed by immunohistochemistry and electron microscopy. No extrahepatic mass was found, despite a thorough systemic survey such as chest and abdominopelvic computed tomography (CT) scans and a whole body positron emission tomography-CT study. To the best of our knowledge, this is the first report of a bona fide primary hepatic neuroblastoma.

Dedifferentiated Extraskeletal Myxoid Chondrosarcoma of the Masticator Space: A Case Report

We describe a 69-year-old woman who presented with a dedifferentiated extraskeletal myxoid chondrosarcoma arising in the left masticator space. Computed tomography and magnetic resonance imaging revealed a 5 cm sized mass in the left masticator space. Histologically, the tumor consisted of two distinct areas. The less cellular area was a low-grade extraskeletal myxoid chondrosarcoma, composed of strands or cords of uniform spindle cells and abundant myxoid stroma. The more cellular, dedifferentiated area corresponded to a high grade myxofibrosarcoma, consisting of anaplastic tumor cells in myxoid stroma and geographic necrosis. The tumor cells of the former area were positive for S-100 protein, microtubule-associated protein-2 (MAP-2) and class III beta-tubulin, but negative for cytokeratin, smooth muscle actin, and desmin. The tumor cells in the latter, pleomorphic area showed MAP-2 and beta-tubulin immunoreactivity with a high Ki-67 labeling index. Based on its histologic and immunohistochemical features, the tumor was considered a dedifferentiated extraskeletal myxoid chondrosarcoma.

Dedifferentiated Extraskeletal Myxoid Chondrosarcoma of the Masticator Space: A Case Report

We describe a 69-year-old woman who presented with a dedifferentiated extraskeletal myxoid chondrosarcoma arising in the left masticator space. Computed tomography and magnetic resonance imaging revealed a 5 cm sized mass in the left masticator space. Histologically, the tumor consisted of two distinct areas. The less cellular area was a low-grade extraskeletal myxoid chondrosarcoma, composed of strands or cords of uniform spindle cells and abundant myxoid stroma. The more cellular, dedifferentiated area corresponded to a high grade myxofibrosarcoma, consisting of anaplastic tumor cells in myxoid stroma and geographic necrosis. The tumor cells of the former area were positive for S-100 protein, microtubule-associated protein-2 (MAP-2) and class III beta-tubulin, but negative for cytokeratin, smooth muscle actin, and desmin. The tumor cells in the latter, pleomorphic area showed MAP-2 and beta-tubulin immunoreactivity with a high Ki-67 labeling index. Based on its histologic and immunohistochemical features, the tumor was considered a dedifferentiated extraskeletal myxoid chondrosarcoma.