The New Kids on the Block: Recently Characterized Soft Tissue Tumors

Immunohistochemistry Update in Dermatopathology and Bone and Soft Tissue Pathology

CONTEXT.—

Immunohistochemistry plays an important role in dermatopathology, particularly for melanocytic lesions and poorly differentiated malignancies. In the field of bone and soft tissue pathology, molecular methods remain the gold standard for diagnosis; however, immunohistochemistry targeting underlying molecular alterations represents a valuable screening tool, especially in areas with limited access to molecular testing.

OBJECTIVE.—

To describe the utility and limitations of new and emerging immunohistochemical stains in the diagnosis of skin, soft tissue, and bone tumors.

DATA SOURCES.—

A literature review of recently described immunohistochemical stains in the fields of dermatopathology and bone and soft tissue pathology was performed.

CONCLUSIONS.—

Immunohistochemistry is an important adjunctive tool for select entities in dermatopathology and bone and soft tissue pathology, and it provides pathologists with valuable evidence of their behavior, underlying molecular alterations, and line of differentiation. Furthermore, immunostains targeting molecular abnormalities have the potential to replace current molecular methods. Many of these recently described stains demonstrate higher sensitivity and specificity; however, limitations and pitfalls still exist, and correlation with morphologic and clinical findings remains essential for diagnosis.

Small biopsies in the head and neck: Bone and soft tissue

Bone and soft tissue lesions in the head and neck encompass not only a broad morphologic spectrum but also significant inherent clinicopathologic overlap. Epidemiology, radiology, and location - similar to the diagnostic assessment in other sites - are especially important considerations in the context of an established mesenchymal proliferation. Herein, the approach towards diagnosis is stratified by morphology (spindle, sarcomatoid, epithelioid, round cell), cellular lineage (fibroblastic, nerve sheath, rhabdomyogenic), and tumor grade (benign, low- to high-grade malignant) as the basis of further immunohistochemical or molecular investigation.

Superficial CD34-Positive Fibroblastic Tumor on the Chest Wall of an 8-Year-Old Girl: A Case Report and Literature Review

This study reports a case of superficial CD34-positive fibroblastic tumor (SCPFT) in a child and analyze the major known clinicopathological features of SCPFT and other skin mesenchymal tumors, contributing to an accurate diagnosis of this rare disease. We summarize the clinicopathologic features of an 8-year-old girl who was diagnosed with SCPFT and 46 previously reported SCPFT cases. Post-operative histopathologic examination of the current case showed the tumor lesion was well-circumscribed; tumor cells were spindled-to-polygonal with a fascicular pattern; most nuclei displayed hyperchromasia and low mitotic rate; intranuclear pseudoinclusions could be found; and abundant eosinophilic cytoplasm and partial myxoid stroma were observed. Immunohistochemistry revealed strong and diffuse CD34-positivity, vimentin staining positively but no S-100, SMA, NSE, CD31, desmin, cytokeratin, STAT6, β-catenin, MDM2, or ERG expression. The Ki-67 and CD68 labeling indexes were approximately 1%. There were no rearrangements of PDGFB or PRDM10 tested by FISH. After surgical resection, the patient had no signs of recurrence or metastasis at a 6-month follow-up. The present case is the first that describes SCPFT in children and has significant clinical implications. SCPFT should be differentiated from other skin mesenchymal tumors. The presented compilation of all so far published SCPFT cases will help in diagnosing successfully SCPFT and increasing awareness of this tumor to guide clinical practice.

Malignant Gastrointestinal Neuroectodermal Tumor: Clinicopathologic, Immunohistochemical, and Molecular Analysis of 19 Cases

A malignant gastrointestinal neuroectodermal tumor (GNET) is rare, and it is therefore yet to be completely understood. This study aimed to present the clinicopathologic features of GNET, including treatment information. We included 19 patients with GNET with a mean tumor size of 4.2 cm. The most common site of tumor origin was the small intestine (57.9%), followed by the stomach (15.8%), colon (10.5%), ileocecal junction (5.3%), lower esophagus (5.3%), and anal canal (5.3%). Microscopically, the tumors were composed of epithelioid cells with eosinophilic or clear cytoplasm arranged in nest, sheet-like, papillary, or pseudoalveolar patterns and/or spindle tumor cells with eosinophilic cytoplasm arranged in a fascicular pattern. Immunohistochemically, the tumor cells stained positively for S100 (19/19,100%), SOX10 (14/15, 93.3%), vimentin (17/17, 100%), synaptophysin (Syn) (7/17, 41.2%), CD56 (4/13, 30.8%), CD99 (1/5, 20%), and CD117 (1/15, 6.7%), and negatively for HMB45, Melan A, DOG1, CD34, AE1/AE3, CAM5.2, chromogranin A, smooth muscle actin, and desmin. In total, 14/15 (93.3%) cases showed split Ewing sarcoma breakpoint region 1 gene (EWSR1) signals consistent with a chromosomal translocation involving EWSR1. Within a mean follow-up of 29.7 months (range: 3 to 63 mo), 2/15 (13.3%) patients died of disease, 5 (33.3%) were alive with disease, and 8 (53.3%) had no evidence of disease. Two and 1 patients showed partial response to apatinib and anlotinib, respectively. In conclusion, GNET has distinctive morphologic, immunohistochemical, and molecular genetic features and should be distinguished from other gastrointestinal tract malignancies. Apatinib and anlotinib might be effective for the treatment of advanced GNET and could prolong patient survival.

Biphenotypic Sinonasal Sarcoma-Case Report and Review of Clinicopathological Features and Diagnostic Modalities

Background  Biphenotypic sinonasal sarcoma is a recently described malignancy showing dual differentiation with both myogenic and neural elements. Due to its histologic similarities to other sinonasal malignancies, it is a diagnostic challenge. Objective  The main purpose of this article is to report a case of biphenotypic sinonasal sarcoma and to consolidate data and provide a comprehensive review regarding pathological differences between biphenotypic sarcoma and other sinonasal malignancies and diagnostic modalities used for biphenotypic sarcoma. Material and Methods  A systematic review of all cases of biphenotypic sinonasal sarcoma was performed using electronic databases (PubMed and Medline). Data collected included age, gender, symptoms, sub-site of origin, immunophenotyping, metastasis, recurrence, treatment, duration of follow-up, and survival outcomes. Results  Ninety-five cases of biphenotypic sarcoma were found with mean age at diagnosis of 52.36 years (range, 24-87 years). Female to male ratio was 2.27:1. Extra-sinonasal extension was present in 28%. Immunophenotyping revealed that S-100 and SMA (smooth muscle actin) were consistently positive, while SOX-10 was consistently negative. PAX3-MAML3 fusion [t (2; 4) (q35; q31.1)] was the most common genetic rearrangement. Surgical excision with or without adjuvant radiotherapy was the most frequent treatment modality used. Recurrence was observed in 32% of cases with follow-up. None of the cases reported metastasis. Three patients had died at the time of publication that included one case with intracranial extension. Conclusion  Biphenotypic sarcoma is distinct sinonasal malignancy with unique clinicopathological features. Testing involving a battery of myogenic and neural immunomarkers is essential for diagnostic confirmation and is a clinically useful endeavor when clinical suspicion is high.

Imaging and Outcomes for a New Entity: Low-Grade Sinonasal Sarcoma with Neural and Myogenic Features

Objectives Low-grade sinonasal sarcoma with neural and myogenic features (LGSSNMF) is a new, rare tumor. Our goal is to describe the imaging characteristics and surgical outcomes of this unique skull base malignancy.

Design Retrospective case series.

Setting Academic medical center.

Participants There were three patients who met inclusion criteria with a confirmed LGSSNMF.

Main Outcome Measures Imaging and histopathological characteristics, treatments, survival and recurrence outcomes, complications, morbidity, and mortality.

Results Patients presented with diplopia, facial discomfort, a supraorbital mass, and nasal obstruction. Magnetic resonance imaging and computed tomography imaging in all cases showed an enhancing sinonasal mass with associated hyperostotic bone formation that involved the frontal sinus, invaded the lamina papyracea and anterior skull base, and had intracranial extension. One patient underwent a purely endoscopic surgical resection and the second underwent a craniofacial resection, while the last is pending treatment. All patients recovered well, without morbidity or long-term complications, and are currently without evidence of disease (mean follow-up of 2.1 years). One patient recurred after 17 months and underwent a repeat endoscopic skull base and dural resection.

Conclusions The surgical outcomes and imaging of this unique, locally aggressive skull base tumor are characterized.

Development of crizotinib, a rationally designed tyrosine kinase inhibitor for non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the number one cause of global mortality. Despite aggressive treatment, the prognosis is dismal. Patients with advanced NSCLC have a median survival of 4 months from the time of diagnosis. Fortunately, molecularly based approaches to drug discovery have yielded a tyrosine kinase inhibitor, crizotinib, which significantly prolongs median progression-free survival in a subset of patients. Although initial clinical trial results demonstrate crizotinib has a promising role to play in NSCLC treatment, development of resistance leaves much to be elucidated about how to effectively combat this deadly disease. In this review, we follow the discovery and development of crizotinib from bench to bedside and provide an example of successful bottom-up drug design. Then, we explore the clinical trial results that fast-tracked its eventual use as a frontline therapy for sensitive NSCLC patients and the development of resistance. Lastly, we discuss the potential for future uses of crizotinib both within and beyond NSCLC.

Aggressive Metastatic Inflammatory Myofibroblastic Tumor After Allogeneic Stem Cell Transplant With Fatal Pulmonary Toxicity From Crizotinib

Inflammatory myofibroblastic tumors (IMTs) are rare tumors with an intermediate spectrum of biological behavior. IMTs are uncommon secondary malignancies after hematopoietic stem cell transplant. The presence of anaplastic lymphoma kinase rearrangements in 50% of IMTs has led to therapeutic trials with crizotinib, although limited experience remains with crizotinib use in children. We describe the first reported case of a highly aggressive and metastatic IMT (secondary malignancy) in an 8-year-old girl following umbilical cord blood transplant. Although tumor response was demonstrated with anaplastic lymphoma kinase inhibition, she later developed fatal pulmonary toxicity from diffuse alveolar damage, a feature felt most likely to be due to crizotinib.