Cyclin E1 Expression and Palbociclib Efficacy in Previously Treated Hormone Receptor-Positive Metastatic Breast Cancer.

Purpose: A large-panel gene expression analysis was conducted to identify biomarkers associated with the effectiveness of adding palbociclib to fulvestrant.

Methods: The PALOMA-3 ( ClinicalTrials.gov identifier: NCT01942135) trial randomly assigned 521 endocrine-pretreated patients with metastatic breast cancer to receive palbociclib plus fulvestrant or placebo plus fulvestrant.

Endometrial Stromal Sarcoma With Hyalinizing Giant Rosettes, Mimicking Low-Grade Fibromyxoid Sarcoma.

We highlight a rare variant pattern of low-grade endometrial stromal sarcoma showing extensive collagenous rosette formation, closely mimicking low-grade fibromyxoid sarcoma. Additionally, this neoplasm showed diffuse and strong expression of muscle markers, favoring an initial diagnosis of leiomyosarcoma. Reverse transcription-polymerase chain reaction showed the presence of JAZF1-SUZ12 fusion transcripts, and this highlights the broad morphologic and immunophenotypic spectrum of endometrial stromal sarcoma.

Warthin Tumor-Like Mucoepidermoid Carcinoma.

Mucoepidermoid carcinoma (MEC) shows a wide morphologic spectrum, including epithelium with oncocytic or squamous metaplastic changes overlying a prominent cystic architecture, as well as tumor-associated lymphoid tissue. We illustrate a case of MEC of the parotid in a 17-year-old female, in which all these features occurred extensively, such that they accounted for almost the entire neoplasm, and closely mimicked Warthin tumor histologically. This highlights the need for diagnostic awareness of this particular morphologic variant of MEC, as patients could potentially be inappropriately discharged from follow-up if diagnosed with a benign neoplasm.

Metastatic Sclerosing Epithelioid Fibrosarcoma in Bone Marrow.

Sclerosing epithelioid fibrosarcoma (SEF) is an aggressive neoplasm thought to be related to low-grade fibromyxoid sarcoma, which typically occurs in middle-aged adults in the deep soft tissues of the lower extremities and trunk. It comprises nests and cords of relatively uniform epithelioid polygonal cells with clear or eosinophilic cytoplasm in densely sclerotic stroma, and it is typically associated with EWSR1 gene rearrangements, and most commonly EWSR1-CREB3L1 fusions. As primary SEF can arise in bone, and bone is also a common metastatic site for SEF, its recognition at this site is important.

Malignant Peripheral Nerve Sheath Tumor With Divergent Glandular Differentiation.

Malignant peripheral nerve sheath tumors (MPNST) are soft tissue neoplasms with evidence of nerve sheath differentiation. They usually arise from peripheral nerves or from preexisting benign nerve sheath neoplasms, often in patients with neurofibromatosis type 1 (NF1). The histologic diagnosis of MPNST is challenging as their morphology is highly variable, and there has been a lack of routine diagnostic immunohistochemical markers and specific genetic aberrations.

Magnetic Resonance Tumor Regression Grade and Residual Mucosal Abnormality as Predictors for Pathological Complete Response in Rectal Cancer Postneoadjuvant Chemoradiotherapy.

Background: Pathological complete response after chemoradiotherapy for rectal cancer occurs in 10% to 30% of patients. The best method to identify such patients remains unclear. Clinical assessment of residual mucosal abnormality is considered the most accurate method.

Solid-Pattern Desmoplastic Small Round Cell Tumor.

Desmoplastic small round cell tumor (DSRCT) is an aggressive small round cell sarcoma that typically occurs intra-abdominally in adolescents and young adults, and is characterized by a recurrent t(11;22)(p13;q12) translocation leading to generation of the EWSR1-WT1 fusion gene, which codes for a chimeric protein with transcriptional regulatory activity. DSRCT has a characteristic histologic appearance of nests of uniform small cells within prominent fibroblastic stroma and immunohistochemically it shows multidirectional differentiation, with expression of epithelial, neural, and muscle markers. We illustrate a case of DSRCT that presented as a large intra-abdominal mass, which harbored EWSR1 rearrangement by fluorescence in situ hybridization and EWSR1-WT1 fusion transcripts by reverse transcription-polymerase chain reaction (RT-PCR), and which histologically had an entirely solid morphology, lacking evidence of desmoplastic stroma.

Interstitial Cells of Cajal in Deep Esophageal Leiomyoma.

Gastrointestinal stromal tumors (GISTs) are potentially aggressive mesenchymal neoplasms with spindle cell, epithelioid, or mixed morphology. They typically express CD117, DOG1, and CD34 and can be diffusely and strongly positive for h-caldesmon. Leiomyomas are benign smooth muscle neoplasms that can arise in a variety of visceral and soft tissue sites, including the gastrointestinal tract.