GLI1-Altered Mesenchymal Tumor with ACTB Fusion and Somatostatin Receptor 2A (SSTR2A) Immunopositivity.

Glioma-associated oncogene (-altered mesenchymal tumors are a newly described entity of neoplasms with very few case reports published in the literature. -altered neoplasms have a moderate degree of variability as they are seen in a broad range of anatomic sites and amongst people of all ages. A common feature that most -altered tumors share is the histologic makeup of monomorphic ovoid cells organized in distinct nests and an arborizing vascular blood supply.

Soft tissue mass resembling myxochondroid metaplasia in Achilles tendon.

The Achilles tendon is the strongest and largest tendon in the human body, composed of the distal confluence of the gastrocnemius and soleus muscles and may also include the plantaris longus tendons. Despite its tremendous strength, it is frequently injured. Soft tissue tumors or tumor-like conditions of Achilles tendon are much less common in comparison to traumatic and infectious/inflammatory lesions.

Low-Level Amplification by FISH: An Institutional Experience With a Diagnostic Dilemma.

() amplification via fluorescence in-situ hybridization (FISH) is the gold standard test used for confirming the diagnosis of atypical lipomatous tumor/well differentiated liposarcoma and dedifferentiated liposarcoma. It is also used as a screening test in high grade spindle cell or pleomorphic neoplasms. FISH is considered positive for amplification when the /CEP12 ratio is greater than 2; however, a ratio between 2 and 3 is considered a "low-level" amplification and raises the possibility of a false positive result; thus, posing a diagnostic dilemma.

Extra-Acral Minute Synovial Sarcoma: A Case Report With Literature Review.

Synovial sarcoma is a malignant soft tissue tumor of uncertain differentiation. It is typically seen in the deep soft tissue of the extremities; however, it has been reported to occur anywhere in the body. Synovial sarcoma by histomorphology has multiple subtypes, including monophasic spindle cell, biphasic and poorly differentiated subtypes.

EMA-Positive Superficial ALK-Rearranged Myxoid Spindle Cell Neoplasm Masquerading as Perineurioma/Hybrid Nerve Sheath Tumor.

Superficial anaplastic lymphoma kinase (ALK)-rearranged myxoid spindle cell neoplasm (SAMS) is a recently described entity which coexpresses ALK, CD34, and commonly S100. These neoplasms are characterized morphologically by concentric spindle cell whorls and cords and are commonly set in an abundant myxoid to myxocollagenous stroma, thus mimicking perineurioma or hybrid nerve sheath tumor. EMA immunostain has been reported to be negative in SAMS which helps in excluding the latter entities.

Myxoid variant of plexiform fibrohistiocytic tumor: case report.

Background: Plexiform fibrohistiocytic tumor (PFH) is a rarely metastasizing slowly growing neoplasm usually affecting children and young adults. The tumor usually has a dermal-subcutaneous location, is poorly circumscribed, and is comprised of a plexiform or multinodular proliferation of a variable admixture of fibroblasts and histiocytoid cells with a distinctive biphasic morphology. Myxoid change in PFH is extremely rare with only five cases of myxoid variant of PFH reported to date in the English literature.

Cytomorphology of metastatic dedifferentiated/undifferentiated melanoma to the gallbladder: A case report and review of literature.

Dedifferentiated/undifferentiated melanoma (DM/UM) is a distinct subtype of malignant melanoma that tends to lose all melanocytic markers of differentiation. DM/UM pose major diagnostic challenges as they could be easily confused with UM sarcoma or carcinoma, thus necessitating the use of molecular studies such as Next Generation Sequencing (NGS) for detecting melanoma-compatible mutations to confirm such diagnosis. The capability of performing NGS molecular studies on small biopsy material with confirmation of adequacy via rapid on-site evaluation (ROSE) has tremendous value in diagnosing DM/UM.

Pulmonary squamous cell carcinoma metastatic to the proximal interphalangeal joint of the right finger: report of a rare case and review of the literature.

Synovial metastasis is a rare condition with only a few cases reported in the literature. Synovial metastasis to the finger or toe joint is different from acrometastasis, which is defined as bone metastasis located distal to the elbow and knee. The most common site of synovial metastasis is the knee joint.

Vascular Neoplasms With NFATC1/C2 Gene Alterations : Expanding the Clinicopathologic and Molecular Characteristics of a Distinct Entity.

Despite significant advances in their molecular pathogenesis, skeletal vascular tumors remain diagnostically challenging due to their aggressive radiologic appearance and significant morphologic overlap. Within the epithelioid category and at the benign end of the spectrum, recurrent FOS/FOSB fusions have defined most epithelioid hemangiomas, distinguishing them from epithelioid hemangioendothelioma and angiosarcoma. More recently, the presence of EWSR1/FUS :: NFATC1/2 fusions emerged as the genetic hallmark of a novel group of unusual vascular proliferations, often displaying epithelioid morphology, with alternating vasoformative and solid growth, variable atypia, reminiscent of composite hemangioendothelioma.

Loss of Histone H3K27 Trimethylation (H3K27me3) Expression as a Potential Diagnostic Pitfall in Sarcomatoid Carcinoma.

Loss of histone H3K27 Trimethylation (H3K27me3) immunohistochemical expression is commonly used as an ancillary test and a surrogate marker for the diagnosis of malignant peripheral nerve sheath tumor (MPNST). A potential histological mimic of MPNST is sarcomatoid carcinoma. Prompted by an index specimen of sarcomatoid carcinoma with H3K27me3 loss and the lack of literature on such phenomenon, we sought to determine the frequency of H3K27me3 loss of expression in a cohort of sarcomatoid carcinomas.

Cytomorphology of a unique case of dedifferentiated chordoma involving a pleural effusion specimen.

Cytomorphology along with positive AE1/AE3 staining and Brachyury staining support the dignosis of metastatic dedifferentiated chordoma.

Expanding the molecular signatures of malignant ossifying fibromyxoid tumours with two novel gene fusions: PHF1::FOXR1 and PHF1::FOXR2.

Aims: Ossifying fibromyxoid tumor (OFMT) is a rare enigmatic tumor of uncertain differentiation that can be classified as typical, atypical, and malignant subtypes based on cellularity, nuclear grade, and mitotic activity. The majority of OFMTs, regardless of the risk of malignancy, harbor genetic translocations. We report two malignant OFMTs, including one with evidence of dedifferentiation, with novel genefusions.

Synchronous polyostotic solid variant of aneurysmal bone cyst involving thoracic vertebrae and harboring a novel AHNAK::USP6 gene fusion. A case report and review.

Aneurysmal bone cyst (ABC) is a benign bone neoplasm that usually affects the metaphysis of long bones and the posterior elements of vertebral bodies. The rearrangement of USP6 gene is present in most of primary ABC cases. Synchronous polyostotic presentation is extremely rare.

Intradural Extramedullary Concurrent Schwannoma and Meningothelial Hyperplasia at C2-C3 Cervical Vertebrae: A Case Report and Review of Literature.

Concomitant schwannomas and benign meningothelial proliferations, including meningothelial hyperplasia or meningioma, rarely occur at the same location outside the setting of neurofibromatosis. Herein, we present a rare case of concurrent schwannoma and benign meningothelial hyperplasia concomitantly occurring in the cervical spine of a 69-year-old male patient with no history of any genetic disorder.

Expanding the Molecular Genetic Spectrum of Bone and Soft Tissue Fibrosarcomas: An Institutional Experience.

Fibrosarcomas, once comprising the majority of unclassifiable spindle-cell sarcomas, are now regarded as a diagnosis of exclusion. Prompted by an index report of neurotrophic receptor tyrosine kinase fusion in fibrosarcomas by Yamazaki et al bone/soft tissue tumors diagnosed as fibrosarcoma at our institution were evaluated in an attempt to expand the genetic spectrum of fibrosarcomas and identify therapeutically targetable cases. Institutional archives were searched for cases diagnosed as "fibrosarcoma" involving bone/soft tissue from 2000 to present.

Prognosis of duodenal gangliocytic paraganglioma with lymph node metastasis: is follow-up >5 years required?

Gangliocytic paragangliomas (GP) are rare tumors encountered exclusively in the second portion of the duodenum. Duodenal gangliocytic paraganglioma (DGP) belongs to a subclass of neuroendocrine neoplasms, characterized with unique histologic features of carcinoid tumor, paraganglioma and ganglioneuromas. According to the recent World Health Organization classification of gastrointestinal neuroendocrine tumors (NETs), there is a debate to classify them either as low-grade NETs or as an independent entity.