Molecularly Confirmed Pseudomyogenic Hemangioendothelioma with Unusual EGFL7::FOSB Fusion in the Head and Neck Region of an Older Patient.

Pseudomyogenic hemangioendothelioma (PMHE), a rare vascular neoplasm, was first described in 1992 asa fibroma-like variant of epithelioid sarcoma, and would be termed as epithelioid sarcoma-like hemangioendothelioma a decade later due to its significant histologic overlap with epithelioid sarcoma and diffuse cytokeratin expression. PHME is currently defined as a distinct, potentially intermediate malignant, rarely metastasizing neoplasm with vascular/endothelial differentiation. It is characterized by young age (typically less than 40 years old), extremity location (approximately ~80%), and t(7:19) SERPINE1::FOSB fusion as the most common molecular alteration. Herein, we report a case of a 59-year-old male presenting with multifocal lesions, including in the right temporalis muscle, right frontoparietal calvarium, right pterygoid muscles, and right mandibular condyle. Histologic examination of the right temporal lesion revealed a multinodular biphasic lesion composed of sheets and fascicles of elongated spindle and epithelioid cells infiltrating into the adjacent skeletal muscle. Admixed abundant neutrophilic infiltration is noted; however, areas of necrosis, increased mitosis, nuclear atypia, or rhabdomyoblast-like cells are absent. Immunohistochemical (IHC) staining showed that the tumor cells were diffusely and strongly positive for FOSB, pan-cytokeratin (AE1/AE3), CD31, and ERG. Molecular testing demonstrated a t(9:19) EGFL7::FOSB fusion mRNA. This constellation of morphological, IHC and molecular findings was consistent with a diagnosis of PMHE. This is the first reported case of multifocal PMHE with EGFL7::FOSB fusion in the head and neck area of a patient aged more than 50 years old. Since the differential diagnoses for PMHE includes high-grade malignancies with aggressive clinical behavior, coupled with the rare reports of PMHE in the head and neck region, awareness of this tumor in the head and neck region will avoid the misdiagnosis and overtreatment of this entity.

A 50-Year-Old Man Presenting with Multiple Bone Lesions and a Diagnosis of Phosphaturic Mesenchymal Tumor of the Femur.

BACKGROUND Phosphaturic mesenchymal tumor (PMT) is an extremely rare mesenchymal neoplasm that is commonly seen in bone and soft tissue. It is associated with a paraneoplastic syndrome, oncogenic osteomalacia, due to tumor-induced urinary phosphate wasting. It is demonstrated to be predominantly mediated by fibroblast growth factor 23 (FGF23)/fibroblast growth factor receptor 1 (FGFR1) axis. Clinically, PMT usually presents as a solitary lesion in the bone. The diagnosis of PMT is challenging due to its non-specific clinical manifestation, radiologic findings, and morphological features. CASE REPORT We report the case of a 50-year-old man presenting with multiple lytic bone lesions and associated pathologic fracture of the right femur, clinically suspicious for multiple myeloma or other metastatic malignant process. Resection from the right femur showed a hypercellular lesion composed of oval-to-spindled cells infiltrating the native trabecular bone with admixed multinucleated giant cells. Immunohistochemical (IHC) staining and in situ hybridization (ISH) demonstrated the tumor cells were positive for SATB2, ERG, FGFR1, and FGF23 ISH. DNA and RNA next-generation sequencing showed marked increases in mRNA levels of FGF23 and FGFR1. The constellation of clinicoradiologic, histomorphologic, IHC, and molecular findings supported a diagnosis of primary benign PMT. CONCLUSIONS This case report discusses a patient with PMT presenting with multifocal lesions due to tumor-induced osteomalacia at initial presentation. We hope that this report will increase the awareness of clinician and pathologists of PMT as a differential diagnosis in patients presenting with multifocal lytic bone lesions. In turn, this will prevent misdiagnosis and overtreatment of a typically benign process.

10-Year observation of a rare presentation of pure fibromyxoid nephrogenic adenoma in the renal pelvis.

Nephrogenic adenoma (NA) is an unusual benign epithelial tumor in the genitourinary tract. Here we report a fibromyxoid nephrogenic adenoma in a 37-year-old female presenting with over 10-year slow-growing renal pelvic mass that was diagnosed with bland spindle cell lesion in multiple previous biopsies. This is the first reported case of pure fibromyxoid NA in renal pelvis with close comparison and correlation of biopsy and resection findings over a 10-year span. This will enhance awareness of pathologists to consider this unusual entity when examining spindle cell lesions in this setting, and prevent misdiagnosis and overtreatment of a typically benign process.

The use of optical coherence tomography and convolutional neural networks to distinguish normal and abnormal oral mucosa.

Incomplete surgical resection of head and neck squamous cell carcinoma (HNSCC) is the most common cause of local HNSCC recurrence. Currently, surgeons rely on preoperative imaging, direct visualization, palpation and frozen section to determine the extent of tissue resection. It has been demonstrated that optical coherence tomography (OCT), a minimally invasive, nonionizing near infrared mesoscopic imaging modality can resolve subsurface differences between normal and abnormal head and neck mucosa. Previous work has utilized two-dimensional OCT imaging which is limited to the evaluation of small regions of interest generated frame by frame. OCT technology is capable of performing rapid volumetric imaging, but the capacity and expertise to analyze this massive amount of image data is lacking. In this study, we evaluate the ability of a retrained convolutional neural network to classify three-dimensional OCT images of head and neck mucosa to differentiate normal and abnormal tissues with sensitivity and specificity of 100% and 70%, respectively. This method has the potential to serve as a real-time analytic tool in the assessment of surgical margins.