Spontaneous regression of "pauci-hemosiderotic" fibrolipomatous tumor.

A 64-year-old man presented with a palpable, soft, compressible, superficial mass on his left lateral hindfoot, with no other symptoms. No significant past medical history. Initial ultrasound and magnetic resonance imaging (MRI) studies characterized the mass as a cyst-like, fluid-containing lesion.

Follicular Dendritic Cell Sarcoma of the Parapharyngeal Space Arising in Association With Castleman Disease.

Follicular dendritic cell sarcoma (FDCS) is a rare malignant neoplasm of follicular dendritic cell origin. It is occasionally associated with unicentric Castleman disease (UCD), particularly the hyaline-vascular (HV) variant (HV-UCD). We report a 56-year-old woman with FDCS arising in the parapharyngeal space in the background of HV-UCD.

Glucose Transporter 1 (GLUT1) Positivity in Ganglion Cysts: A Diagnostic Caveat Due to Overlap With Perineuriomas and Other Fibromyxoid Lesions.

Glucose transporter 1 (GLUT1) is a sensitive immunohistochemical marker for perineural cells and certain mesenchymal neoplasms, including chordoma, desmoplastic small round cell tumor, desmoid-type fibromatosis, epithelioid sarcoma, gastrointestinal stromal tumor, myoepithelioma, schwannoma, and undifferentiated pleomorphic sarcoma. In this study, we focus on the morphological and immunohistochemical challenges in differentiating between ganglion cysts and perineuriomas. To our knowledge, no previous studies have explored the potential morphological and immunohistochemical similarities between these two lesions.

Osteoid Osteoma in an Elderly Patient: Diagnostic Challenges.

Osteoid osteoma is a benign bone tumor commonly affecting young individuals, with a rare occurrence in older adults. It typically presents with night pain relieved by nonsteroidal anti-inflammatory drugs and is characterized radiographically by a small, radiolucent nidus surrounded by reactive sclerosis. We present a 70-year-old female patient with persistent right hip pain, initially diagnosed as arthritis, who underwent total hip arthroplasty.

Intraosseous mandibular clear cell odontogenic carcinoma with predominant small round blue cells: a potential diagnostic pitfall.

Objective: Clear cell odontogenic carcinoma (CCOC) is a rare malignancy of the jaw, presenting significant diagnostic challenges. This report aims to highlight the complexities associated with biopsy-based diagnoses of oral and maxillofacial lesions, as demonstrated in a case of intraosseous mandibular CCOC initially suggestive of Ewing's sarcoma due to its presentation with small round blue cells.

Results: The patient, a 37-year-old male, presented with a mandibular lesion that on incisional biopsy was suggestive of Ewing's sarcoma.

Mycobacterial spindle cell pseudotumor of the spinal cord: Case report and literature review.

We report the first description of spinal cord mycobacterial spindle cell pseudotumor. A patient with newly diagnosed advanced HIV presented with recent-onset bilateral leg weakness and was found to have a hypermetabolic spinal cord mass on structural and molecular imaging. Biopsy and cultures from blood and cerebrospinal fluid confirmed spindle cell pseudotumor due to Mycobacterium avium-intracellulare.

Sarcoma Cells Secrete Hypoxia-Modified Collagen VI to Weaken the Lung Endothelial Barrier and Promote Metastasis.

Unlabelled: Intratumoral hypoxia correlates with metastasis and poor survival in patients with sarcoma. Using an impedance sensing assay and a zebrafish intravital microinjection model, we demonstrated here that the hypoxia-inducible collagen-modifying enzyme lysyl hydroxylase PLOD2 and its substrate collagen type VI (COLVI) weaken the lung endothelial barrier and promote transendothelial migration. Mechanistically, hypoxia-induced PLOD2 in sarcoma cells modified COLVI, which was then secreted into the vasculature.

Myofibroblastoma in the Liver: A Case Report and Review of Literature.

Myofibroblastoma is a rare benign mesenchymal tumor first described in the breast. It is also known as mammary-type myofibroblastoma outside of the breast, more frequently located along the embryonic milk line. Exceptionally, myofibroblastoma can occur at visceral locations.

Anisometric Cell/Dysplastic Lipomas in a Retinoblastoma Survivor: Report of a Case with Review of the Literature.

Different authors have recently described a subtype of lipoma characterized by variation of adipocyte size, single cell fat necrosis, and a subset with minimal to mild nuclear atypia, and termed these as anisometric cell/dysplastic lipoma (AC/DL). These lipomas follow a benign course and rarely recur. In 3 examples, AC/DL has occurred in patients with childhood retinoblastoma (RB).

Atypical Spindle Cell and Pleomorphic Lipomatous Tumor of the Ocular Adnexa: Two Cases of a Rare Entity.

Atypical spindle cell and pleomorphic lipomatous tumor (ASCPLT) is a rare lipomatous neoplasm that was recently introduced into the World Health Organization Classification of Soft Tissue and Bone tumors as a distinct entity. ASCPLT has potential for local recurrence but does not metastasize. This biologic behavior separates ASCPLT from its morphologic mimics.

S100 and CD34 Expressing Mesenchymal Neoplasm With Rare PLEKHH2::ALK Fusion and Response to ALK Inhibition.

The PLEKHH2::ALK fusion is a rarely reported gene fusion identified predominantly in lung adenocarcinomas. Tumors with this fusion have been reported to be of durable response to ALK inhibitors. We herein present the case of a 21-year-old woman with a histomorphologically heterogenous mesenchymal neoplasm of the pelvis, expressing both s100 and CD34, with subsequently identified PLEKHH2::ALK fusion.

Clinical, pathologic, and molecular analyses of superficial low-grade fibromyxoid sarcoma in two young patients: A rare and deceptive mimic of benignancy.

Low-grade fibromyxoid sarcoma (LGFMS) is a histopathologically deceptive soft tissue neoplasm with bland cytology, which is typically encountered in deep soft tissue of adults. We report two cases of superficial LGFMS in young patients (16 and 21 years old, respectively), which were difficult to diagnose on histopathologic and clinical findings alone. LGFMS commonly mimics benign neoplasms such as cellular neurothekeoma, fibromatosis, neurofibroma, and perineurioma.

Metastatic Meningioma of the Neck: A Case Report and Systematic Review.

Background: Although meningiomas are the most common central nervous system neoplasms, extracranial metastases are exceedingly rare. There are even fewer reports of metastatic meningiomas to the neck.

Methods: We described a patient with multiply recurrent orbital meningioma with metastasis to the neck found incidentally during neck exploration for composite resection and free tissue reconstruction.

Focal reactive periostitis ossificans in a long bone: radiologic and pathologic findings.

Florid reactive periostitis ossificans (FRPO) is a benign juxta-cortical lesion of unknown etiology which most commonly occurs in the hands and feet. We report the radiographic, CT, and MR features of a pathologically confirmed FRPO in the distal femur, a location in which only a handful of cases has been reported. A 26-year-old male who presented with distal thigh pain initially underwent radiograph and CT, which illustrated a well-circumscribed, ossified lesion associated with the cortex of the femur without contiguity with the medullary canal.

Electric field-enhanced electrochemical CRISPR biosensor for DNA detection.

DNA detection plays an important role in the rapid screening of cancers and early diagnosis of infectious diseases. Here, we developed a simple, versatile, electric field-enhanced (EFE), electrochemical CRISPR biosensor to detect DNA targets in a homogeneous solution phase. To improve the detection sensitivity, we applied a pulsed electric field to enrich nucleic acids on the electrode surface.

Keratin Granulomas in the Peritoneum on Frozen Section: A Case Report with Multiple Suspects and the Search for the Culprit.

Keratin granulomas in the peritoneum are a rare finding with multiple etiologies and can be especially challenging for both the pathologist and the surgeon when these lesions are grossly visible. We report a case of a unique frozen section diagnostic scenario of evaluation of keratin granulomas in the peritoneum of a 47-year-old woman in the setting of multiple potential culprits: endometrial endometrioid adenocarcinoma following fertility sparing treatment, and a concurrent dermoid cyst. We discuss the various etiologies of keratin granulomas in the peritoneum, mechanism of their formation, diagnostic significance, as well as implications of fertility sparing treatments.

Dedifferentiated and undifferentiated neoplasms: A conceptual approach.

This review provides a conceptual approach to dedifferentiation across a variety of tumor types, with particular attention to genetic events that tie together morphologically disparate areas of these neoplasms. First, working definitions of the terms differentiated, undifferentiated, and dedifferentiated are developed. Then, specific examples of tumors with a particular propensity for undergoing dedifferentiation are highlighted, with emphasis on both immunohistochemical studies and molecular lesions that enable surgical pathologists to establish diagnostic clarity in morphologically vexing situations.

Histiocytic and dendritic cell neoplasms of the mediastinum.

In this review, we discuss a logical approach to diagnosis of histiocytic and dendritic cell lesions of the mediastinum. We break down the differential diagnosis between true neoplasms of histiocytic and dendritic cells [Rosai-Dorfman disease (RDD), Langerhans cell histiocytosis (LCH), and follicular dendritic cell sarcoma (FDCS)] versus selected neoplasms of other lineages which frequently attract non-neoplastic histiocytes or resemble them morphologically (carcinoma, melanoma, sarcoma, germinoma, mesothelioma, and lymphoma). As neoplasms in the latter category are more common, they should be stringently excluded before diagnosing a lesion in the first group, particularly given enormous differences in clinical management.

Penn Medicine Head and Neck Cancer Service Line COVID-19 management guidelines.

Introduction: The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus has altered the health care environment for the management of head and neck cancers. The purpose of these guidelines is to provide direction during the pandemic for rational Head and Neck Cancer management in order to achieve a medically and ethically appropriate balance of risks and benefits.

Methods: Creation of consensus document.

Real-time Colorimetric Quantitative Molecular Detection of Infectious Diseases on Smartphone-based Diagnostic Platform.

Rapid diagnostics of infectious diseases and accurate identification of their causative pathogens play a crucial role in disease prevention, monitoring, and treatment. Conventional molecular detection of infectious pathogens requires expensive equipment and well-trained personnel, thus limiting its use in centralized clinical laboratories. To address this challenge, a portable smartphone-based quantitative molecular detection platform, termed "smart connected pathogen tracer" (SCPT), has been developed for pathogen monitoring and disease surveillance.

68Ga-DOTATATE Uptake in an Endolymphatic Sac Tumor: Radiologic-Pathologic Correlation.

After dedicated CT and MRI, Ga-DOTATATE PET/CT was performed in a patient with a temporal bone mass with primary diagnostic considerations of an endolymphatic sac tumor versus a glomus jugulotympanicum paraganglioma. The Ga-DOTATATE PET showed mild radiotracer uptake in the mass (SUVmax, 10.9).

A subset of sinonasal undifferentiated carcinoma is associated with transcriptionally active high-risk human papillomavirus by in situ hybridization: a clinical and pathologic analysis.

Sinonasal undifferentiated carcinoma (SNUC) is an aggressive malignancy with a poor prognosis, and pathologically, it is a diagnosis of exclusion. Rendering this diagnosis can be challenging in practice because of the large number of diverse entities in the differential diagnosis. We encountered an index case of a sinonasal carcinoma otherwise diagnosable as SNUC which, on further investigation, demonstrated strong and diffuse P16 expression, as well as diffuse expression of high-risk human papillomavirus (hrHPV) RNA by in situ hybridization (ISH).