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Abstract Vascular abnormality of the intestine is rare, except angiodysplasia. We report on an unusual case of atypical florid vascular proliferations of the appendix. A 41-year old male presented with melena. Adhesioned blood clots in the appendiceal orifice were observed by colonoscopy. He underwent laparoscopic appendectomy. Microscopically, a tiny exophytic polypoid mass was observed. The mass showed pyogenic granuloma-like features in the superficial portion and infiltrative florid vascular proliferations in the deeper portion. Endothelial cells showed minimal nuclear atypia, and mitotic figures were observed infrequently and showed positivity for CD31 and CD34 and negativity for HHV-8. Differential diagnoses include from benign vascular tumor to angiosarcoma or Kaposi’s sarcoma, but this lesion does not fit the description of any defined vascular entity. We diagnosed atypical florid vascular proliferations and the patient has been well during the five-month postoperative follow-up. Virtual Slide The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1386921325843104

Hepatic mesenchymal tumors (HMTs) are non-epithelial benign and malignant tumors with or without specific mesenchymal cell differentiation. They are relatively uncommon. Except for mesenchymal hamartoma, calcified nested stromal–epithelial tumor, and embryonal sarcoma, most mesenchymal lesions are not specific to the liver. Pathologists face challenges in diagnosing HMTs due to their diverse morphologies and phenotypic variations. Accurate diagnosis is critical for directing appropriate patient care and predicting outcomes. This review focuses on mesenchymal tumors with a relative predilection for the liver, including vascular and non-vascular mesenchymal neoplasms. It provides a thorough and up-to-date overview, concentrating on clinical and pathological features, differential diagnosis, and diagnostic approaches. [ABSTRACT FROM AUTHOR]

Individuals harboring germ-line DICER1 mutations are predisposed to a rare cancer syndrome, the DICER1 Syndrome or pleuropulmonary blastoma-familial tumor and dysplasia syndrome [online Mendelian inheritance in man (OMIM) #601200]. In addition, specific somatic mutations in the DICER1 RNase III catalytic domain have been identified in several DICER1-associated tumor types. Pituitary blastoma (PitB) was identified as a distinct entity in 2008, and is a very rare, potentially lethal early childhood tumor of the pituitary gland. Since the discovery by our team of an inherited mutation in DICER1 in a child with PitB in 2011, we have identified 12 additional PitB cases. We aimed to determine the contribution of germ-line and somatic DICER1 mutations to PitB. We hypothesized that PitB is a pathognomonic feature of a germ-line DICER1 mutation and that each PitB will harbor a second somatic mutation in DICER1. Lymphocyte or saliva DNA samples ascertained from ten infants with PitB were screened and nine were found to harbor a heterozygous germ-line DICER1 mutation. We identified additional DICER1 mutations in nine of ten tested PitB tumor samples, eight of which were confirmed to be somatic in origin. Seven of these mutations occurred within the RNase IIIb catalytic domain, a domain essential to the generation of 5p miRNAs from the 5' arm of miRNA-precursors. Germ-line DICER1 mutations are a major contributor to PitB. Second somatic DICER1 "hits" occurring within the RNase IIIb domain also appear to be critical in PitB pathogenesis.

Anaplastic lymphoma kinase (ALK) is detected in both normal and oncological developmental tissues. Among ALK-related tumors, superficial ALK-rearranged myxoid spindle cell neoplasm (SAMS) is a rare, soft tissue tumor characterized by the immunophenotypical co-expression of CD34 and S100. Here, we describe a patient with this rare tumor and outline its clinical and radiological characteristics. A 28-year-old woman with diabetes, hypertension, and panic disorder presented with discomfort caused by a rubbery mass on the left buttock that had persisted for 10 years. Computed tomography revealed a multilobulated hypodense mass with small internal enhancing foci, posing challenges for the exact diagnosis of the lesion. The entire lesion was excised with clear resection margins. An 8.0 × 6.0 cm, well-circumscribed tumor with a lobular growth pattern was observed in the deep subcutaneous tissue. Light microscopy revealed epithelioid, ovoid, and spindle-shaped cells with a reticular cordlike pattern. Immunohistochemistry results were positive for S100, CD34, and vimentin. Break-apart fluorescence in situ hybridization assay results for ALK were also positive. These findings were consistent with those of SAMS. This case suggests that SAMS should be considered when identifying large nonspecific masses during clinical and imaging evaluation. [ABSTRACT FROM AUTHOR]

Simple Summary: Intrahepatic cholangiocarcinoma (ICCA) is the second most common type of primary liver malignancy after hepatocellular carcinoma (HCC). ICCA is characterized by molecular heterogeneity and a diverse histopathological spectrum. Generally, the prognosis for patients diagnosed with ICCA is poor. Recent advances have improved our understanding of the molecular genetics and histological subtypes of ICCA. An accurate diagnosis of ICCA is important for patient management and prognosis. This review aims to provides an updated overview of the pathology of ICCA, with a particular focus on its molecular genetics, histological subtypes, and the diagnostic approaches necessary to distinguish it from other diseases. Intrahepatic cholangiocarcinoma (ICCA) is a malignant epithelial neoplasm characterized by biliary differentiation within the liver. ICCA is molecularly heterogeneous and exhibits a broad spectrum of histopathological features. It is a highly aggressive carcinoma with high mortality and poor survival rates. ICCAs are classified into two main subtypes: the small-duct type and large-duct types. These two tumor types have different cell origins and clinicopathological features. ICCAs are characterized by numerous molecular alterations, including mutations in KRAS, TP53, IDH1/2, ARID1A, BAP1, BRAF, SAMD4, and EGFR, and FGFR2 fusion. Two main molecular subtypes—inflammation and proliferation—have been proposed. Recent advances in high-throughput assays using next-generation sequencing have improved our understanding of ICCA pathogenesis and molecular genetics. The diagnosis of ICCA poses a significant challenge for pathologists because of its varied morphologies and phenotypes. Accurate diagnosis of ICCA is essential for effective patient management and prognostic determination. This article provides an updated overview of ICCA pathology, focusing particularly on molecular features, histological subtypes, and diagnostic approaches. [ABSTRACT FROM AUTHOR]

Cutaneous neoplasms entirely or predominantly composed of spindle cells constitute a heterogeneous group of mesenchymal and nonmesenchymal tumors. Cutaneous spindle cell neoplasms are often diagnostically challenging because of considerable morphologic [...], * Context.--Spindle cell neoplasms arising in the skin comprise a heterogeneous group of tumors with divergent lineages. Cutaneous spindle cell neoplasms are relatively common and present surgical pathologists with diagnostic challenges. Recognition of their histopathologies is important for correct diagnosis and management. The current review presents a pattern-based diagnostic approach to common cutaneous spindle cell neoplasms that often cause diagnostic difficulties. Objective.--To provide a useful guide for diagnosis of cutaneous spindle cell neoplasms. Data Sources.--PubMed (US National Library of Medicine) reports and the authors' personal experiences are reviewed. Conclusions.--The authors briefly summarize the histologic features and differential diagnoses of common cutaneous spindle cell neoplasms. doi: 10.5858/arpa.2018-0112-RA