An Undifferentiated Primary Mediastinal Carcinoma Compressing the Main Pulmonary Artery: A Rare Cause of Right Ventricular Strain.

Undifferentiated carcinoma (or poorly differentiated carcinoma) of the mediastinum is a relatively rare pathological variant of anterior mediastinal tumors. Pathologists usually use the term to describe an epithelial tumor with no histological features that enable the identification of its site of origin. Invasion of adjacent vital cardiopulmonary structures is among the most problematic complications of anterior mediastinal masses. We report a case of a 60-year-old male presenting with easy fatiguability, significant weight loss, and chest pain. A CT scan of the chest revealed a large anterior mediastinal mass, compression of the main pulmonary artery, and a large pericardial effusion. The patient underwent pericardiocentesis, emergent radiotherapy, and platinum-based chemotherapy. His condition dramatically improved, and he was subsequently discharged home for further follow-up.

EBV-positive diffuse large B-cell lymphoma presenting as symptomatic masses in the bladder trigone and unilateral kidney.

Diffuse large B-cell lymphoma (DLBCL) of the genitourinary tract is a rare diagnosis. A 66-year-old male with a history of multiple myeloma and prostate cancer presented with gross hematuria and concern for urinary clot retention. Imaging demonstrated an incidental mass in the left kidney and urinary bladder. Resection of the urinary bladder tumor and biopsy of the kidney revealed Epstein-Barr Virus positive DLBCL. Significant lymphadenopathy was found during staging, and this lymphoma was classified as stage IV. The patient was referred to medical oncology, initiated on chemotherapy, and scheduled for follow up with urology for the renal mass.

Myeloid Sarcoma of the Bladder in the Setting of Refractory Anemia with Excess Blasts-2 (RAEB-2).

Myeloid sarcoma is an extramedullary tumor consisting of immature hematopoietic cells of granulocytic or monocytic differentiation. While rare, it can be seen in a variety of clinical settings and is most commonly associated with acute myeloid leukemia (AML), myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN). We present a rare case of myeloid sarcoma occurring in the bladder of a 56 year old male. Myeloid sarcoma may be difficult to recognize due to its rarity and clinical and morphologic similarity to many other conditions; however, swift diagnosis is necessary as it is considered equivalent to AML. Prognostic indicators for myeloid sarcoma have not been well established, but survival may be improved by undergoing chemotherapy designed to treat AML.

Embryonic origins of the mouse superior olivary complex.

Many areas of the central nervous system are organized into clusters of cell groups, with component cell groups exhibiting diverse but related functions. One such cluster, the superior olivary complex (SOC), is located in the ventral auditory brainstem in mammals. The SOC is an obligatory contact point for most projection neurons of the ventral cochlear nucleus and plays central roles in many aspects of monaural and binaural information processing. Despite their important interrelated functions, little is known about the embryonic origins of SOC nuclei, due in part to a paucity of developmental markers to distinguish individual cell groups. In this report, we present a collection of novel markers for the developing SOC nuclei in mice, including the transcription factors FoxP1, MafB, and Sox2, and the lineage-marking transgenic line En1-Cre. We use these definitive markers to examine the rhombic lip and rhombomeric origins of SOC nuclei and demonstrate that they can serve to uniquely identify SOC nuclei and subnuclei in newborn pups. The markers are also useful in identifying distinct nuclear domains within the presumptive SOC as early as embryonic day (E) 14.5, well before morphological distinction of individual nuclei is evident. These findings indicate that the mediolateral and dorsoventral position of SOC nuclei characteristic of the adult brainstem is established during early neurogenesis.

Molecular guidance cues necessary for axon pathfinding from the ventral cochlear nucleus.

During development, multiple guidance cues direct the formation of appropriate synaptic connections. Factors that guide developing axons are known for various pathways throughout the mammalian brain; however, signals necessary to establish auditory connections are largely unknown. In the auditory brainstem the neurons whose axons traverse the midline in the ventral acoustic stria (VAS) are primarily located in the ventral cochlear nucleus (VCN) and project bilaterally to the superior olivary complex (SOC). The circumferential trajectory taken by developing VCN axons is similar to that of growing axons of spinal commissural neurons. Therefore, we reasoned that netrin-DCC and slit-robo signaling systems function in the guidance of VCN axons. VCN neurons express the transcription factor, mafB, as early as embryonic day (E) 13.5, thereby identifying the embryonic VCN for these studies. VCN axons extend toward the midline as early as E13, with many axons crossing by E14.5. During this time, netrin-1 and slit-1 RNAs are expressed at the brainstem midline. Additionally, neurons within the VCN express RNA for DCC, robo-1, and robo-2, and axons in the VAS are immunoreactive for DCC. VCN axons do not reach the midline of the brainstem in mice mutant for either the netrin-1 or DCC gene. VCN axons extend in pups lacking netrin-1, but most DCC-mutant samples lack VCN axonal outgrowth. Stereological cell estimates indicate only a modest reduction of VCN neurons in DCC-mutant mice. Taken together, these data show that a functional netrin-DCC signaling system is required for establishing proper VCN axonal projections in the auditory brainstem.