Identification and functional characterization of transcriptional activators in human cells.

Transcription is orchestrated by thousands of transcription factors (TFs) and chromatin-associated proteins, but how these are causally connected to transcriptional activation is poorly understood. Here, we conduct an unbiased proteome-scale screen to systematically uncover human proteins that activate transcription in a natural chromatin context. By combining interaction proteomics and chemical inhibitors, we delineate the preference of these transcriptional activators for specific co-activators, highlighting how even closely related TFs can function via distinct cofactors. We also identify potent transactivation domains among the hits and use AlphaFold2 to predict and experimentally validate interaction interfaces of two activation domains with BRD4. Finally, we show that many novel activators are partners in fusion events in tumors and functionally characterize a myofibroma-associated fusion between SRF and C3orf62, a potent p300-dependent activator. Our work provides a functional catalog of potent transactivators in the human proteome and a platform for discovering transcriptional regulators at genome scale.

Inflammatory Myofibroblastic Tumor Presenting as Gross Hematuria in a Pediatric Patient With VACTERL Syndrome Following Bladder Augmentation.

Inflammatory myofibroblastic tumors (IMT) are rare and poorly understood inflammatory neoplasms. Most commonly occurring in the liver and gastrointestinal tract, cases of bladder involvement have been rarely reported. Bladder IMT generally presents with gross hematuria and can be differentiated from other bladder tumors by expression of anaplastic lymphoma kinase. We report the occurrence of an Bladder IMT detected following lower urinary tract reconstruction with bladder augmentation.

A Distinctive Genomic and Immunohistochemical Profile for NOTCH3 and PDGFRB in Myofibroma With Diagnostic and Therapeutic Implications.

Introduction. Myofibromas are rare tumors of pericytic lineage, typically affecting children, and are sometimes aggressive. A subset of sporadic and familial myofibromas have activating variants in PDGFRB. The relationship of myofibroma and PDGFRB to the NOTCH pathway has not yet been described. Methods. Ten myofibroma cases were sequenced with a targeted panel of 447 genes, including copy number variation and selected fusions. Immunohistochemical analysis of total NOTCH3 and activated NOTCH3 was assessed for all 10 myofibroma cases, and a series of histologic mimics (n = 20). Results. Alterations identified by next-generation sequencing included PDGFRB sequence variants in 8/10 cases (80%), a NOTCH3 variant in 1/10 cases (10%), and a NOTCH2 variant in 1/10 cases (10%). All 10 cases also showed a pattern of low-amplitude (1.5- to 2-fold) copy number alterations including gains in PDGFRB and NOTCH3. Ten of 10 myofibromas (100%) showed cytoplasmic staining for total NOTCH3 and 9 of 10 cases (90%) showed nuclear staining for activated NOTCH3. Within the control cohort of histologic mimics, 3 of 3 nodular fasciitis cases (100%) were positive for activated and total NOTCH3, and the remaining 17 cases were negative for pan NOTCH3, while 3 of 3 desmoid-type fibromatosis cases (100%) showed patchy weak nuclear staining for activated NOTCH3. Discussion. Our findings suggest a common pathway of PDGFRB/NOTCH3 activation in myofibromas, even in cases that lack PDGFRB sequence variants. These results support the pericytic lineage of myofibroma. Identification of the characteristic genomic alterations or immunohistochemical staining pattern may facilitate a difficult pathologic diagnosis, and support the use of targeted treatments.

PD-L1 expression in inflammatory myofibroblastic tumors.

Inflammatory myofibroblastic tumor is a rare mesenchymal tumor occurring at many anatomic sites, with a predilection for children and young adults. Often indolent, they can be locally aggressive and can metastasize, resulting in significant morbidity and mortality. Therapeutic options are often limited. The identification of underlying kinase mutations has allowed the use of targeted therapy in a subset of patients. Unfortunately, not all tumors harbor mutations and resistance to tyrosine kinase inhibitor therapy is a potential problem. We hypothesized that these tumors may be amenable to PD-L1 therapy given the immune nature of the tumor. PD-L1 expression in inflammatory myofibroblastic tumors has not yet been defined. The purpose of this study was to explore PD-L1 expression in inflammatory myofibroblastic tumors, as adaptive PD-L1 expression is known to enrich for response to anti-PD-1/PD-L1 therapies. Expression of PD-L1 (clone SP142) was assessed in 35 specimens from 28 patients. Positivity was defined as membranous expression in ≥5% of cells and evaluated separately in tumor and immune cells. Adaptive vs. constitutive patterns of tumor cell PD-L1 expression were assessed. PD-L1 status was correlated with clinicopathologic features. CD8+ T cell infiltrates were quantified by digital image analysis. ALK status was assessed by immunohistochemistry and/or FISH. Twenty-four (69%) tumors had PD-L1(+) tumor cells and 28 (80%) showed PD-L1(+) immune cells. Most recurrent and metastatic tumors (80%) and ALK(-) tumors (88%) were PD-L1(+). Adaptive PD-L1 expression was present in 23 (96%) of PD-L1(+) tumors, which also showed a three-four fold increase in CD8+ T cell infiltration relative to PD-L1(-) tumors. Constitutive PD-L1 expression was associated with larger tumor size (p = 0.002). Inflammatory myofibroblastic tumors show frequent constitutive and adaptive PD-L1 expression, the latter of which is thought to be predictive of response to anti-PD-1. These data support further investigation into PD-1/PD-L1 blockade in this tumor type.

Plexiform angiomyxoid myofibroblastic tumor of the stomach: A case report.

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a rare mesenchymal tumor of the stomach. To date, about 40 cases of PAMT have been reported in the literature. This tumor is not specific in clinical manifestations and microscopically characterized by a plexiform growth pattern. Here, we report the case of an 11-year-old male patient who was diagnosed with PAMT. He had a complaint of right epigastric discomfort with episodic pain, gastroscopy displayed a submucosal bulge at the pylorus, and CT showed a mass in the right abdomen with uneven, delayed enhancement, and a partial gastrectomy revealed a tumor at the pylorus. Histologically, the tumor was multinodular and rich in blood vessels with thin wall; the interstitium had abundant myxomatous stroma; the tumor cells were spindle-shaped, star-shaped, or oval. Immunohistochemically, the tumor cells were positive for Calponin, Caldesmon, and SMA, but negative for CD34, ALK, S-100, desmin, CD117, and Dog-1. This patient was followed up for 12 months, and recurrence or metastasis was not observed. Diagn. Cytopathol. 2017;45:55-58. © 2016 Wiley Periodicals, Inc.

Multicentric myofibromatosis presenting as a large congenital eyelid myofibroma.

Infantile myofibromatosis is a rare mesenchymal neoplasm that commonly involves the head and neck but rarely the eyelid. We report the case of a newborn boy referred for evaluation of a left eyelid lesion that occluded the visual axis. Urgent biopsy was performed to evaluate for malignancy. Histopathologic analysis demonstrated myofibroma. Although these lesions have been reported to regress spontaneously, debulking surgery was performed to prevent sensory or anisometropic amblyopia. Follow-up systemic evaluation revealed numerous subcutaneous and deep soft tissue lesions. There was no visceral involvement.

Head and neck solitary infantile myofibroma: Clinicopathological and immunohistochemical features of a case series.

Infantile myofibroma is a rare mesenchymal benign tumor mostly found in the head and neck region. The aim of this study was to describe a small case series of head and neck solitary infantile myofibroma, emphasizing the importance of the histopathological and immunohistochemical features, and the potential diagnostic challenges. For the study, clinical and imaging data were obtained from the medical records. All cases were histologically reviewed, and immunohistochemical analyses were performed to confirm the diagnosis. Four cases of head and neck solitary infantile myofibroma were identified. All patients were females and presented a mean age of 3 years old (ranging from 2 to 6 years). The site of the tumors were the mandible, right cheek, subcutaneous tissue adjacent to basal cortical of the mandible and upper anterior gingiva. No symptoms, such as pain or paresthesia, were reported. Computerized tomography revealed well-delimited tumors. All tumors were positive for vimentin and alpha-smooth muscle actin. All patients underwent surgical excision and no signs of recurrence were observed after long-term follow-up. In summary, head and neck solitary infantile myofibromas are rare and present excellent prognosis. The correlation between clinical, histopathological and immunohistochemical features are essential for a correct diagnosis.

Expression of ROS1 predicts ROS1 gene rearrangement in inflammatory myofibroblastic tumors.

Inflammatory myofibroblastic tumor is a distinctive, rarely metastasizing mesenchymal neoplasm composed of fascicles of spindle cells with a prominent inflammatory infiltrate. Roughly 50% of inflammatory myofibroblastic tumors harbor ALK receptor tyrosine kinase gene rearrangements. Such tumors are usually positive for ALK by immunohistochemistry. The molecular pathogenesis of ALK-negative inflammatory myofibroblastic tumors is largely unknown. A recent study identified rearrangements of ROS1 (another tyrosine kinase receptor) in a subset of ALK-negative inflammatory myofibroblastic tumors. Immunohistochemistry for ROS1 has been shown to correlate with ROS1 rearrangement in lung adenocarcinomas. The purpose of this study was to determine whether immunohistochemistry for ROS1 could predict ROS1 rearrangement in inflammatory myofibroblastic tumor. In total, 30 inflammatory myofibroblastic tumors were evaluated, including 21 ALK-positive tumors (10 confirmed to harbor ALK rearrangements, with TPM3, CLTC, RANPB2, and FN1 fusion partners) and 9 ALK-negative tumors (including 2 known to harbor ROS1 rearrangements). Immunohistochemistry was performed on whole tissue sections following pressure cooker antigen retrieval using a rabbit anti-ROS1 monoclonal antibody. The results were scored as 'positive' or 'negative,' and the pattern of staining was recorded. Three ALK-negative inflammatory myofibroblastic tumors (including both tumors with known ROS1 rearrangements) showed immunoreactivity for ROS1, whereas all ALK-positive inflammatory myofibroblastic tumors were negative for ROS1. One ROS1-positive inflammatory myofibroblastic tumor (with YWHAE-ROS1 fusion) showed strong, diffuse cytoplasmic and nuclear staining; one case (with TFG-ROS1 fusion) showed weak, diffuse and dot-like cytoplasmic staining; and one case (fusion partner unknown) showed moderate, diffuse and dot-like cytoplasmic staining. Expression of ROS1 correlates with ROS1 gene rearrangement in inflammatory myofibroblastic tumor. These findings suggest that immunohistochemistry for ROS1 may be useful to support the diagnosis of a subset of inflammatory myofibroblastic tumors and may select some clinically aggressive cases for targeted therapy directed against ROS1.

Mandibular swelling in a 5-year-old child--mandibular myofibroma.

A 5-year-old girl of African descent presented with a history of progressive painless swelling on the right side of the jaw since the past 2-3 months. Orthopantomogram showed a radiolucent lesion near the angle of the mandible. Subsequent CT scan revealed a 2 cm×2 cm radiolucent lesion with intense periosteal reaction surrounding the lesion and destruction of the overlying cortex. Radiological perplexity aroused regarding the possibility of eosinophilic granuloma or some other malignant lesion. Incisional biopsy performed and microscopy showed spindle cell tumor. Immunohistochemistry confirmed it as myofibroma. Myofibroma is a rare benign tumour involving mesenchyme. Involvement of the mandible is rare. Radiological presentation with strong periosteal reaction is a rarity and has rarely been reported in the medical literature. We conclude that intraosseous myofibroma can sometimes have strong periosteal reaction and careful radiological evaluation is a prerequisite for accurate diagnosis and to avoid unnecessary aggressive therapy.

An inflammatory myofibroblastic tumor exhibiting immunoreactivity to KIT: a case report focusing on a diagnostic pitfall.

Inflammatory myofibroblastic tumors (IMTs) and gastrointestinal stromal tumors (GISTs) are both spindle cell tumors, and occur rarely in the wall of the urinary bladder. In general, immunostaining allows differentiation of IMTs and GISTs. Most IMTs are positive for anaplastic lymphoma kinase (ALK) and negative for KIT, whereas most GISTs are ALK-negative and KIT-positive. Here, we describe a case of a spindle cell tumor in the wall of the urinary bladder. The spindle cells were positive for both ALK and KIT, and it was thus difficult to determine whether the tumor was an IMT or a GIST. We eventually diagnosed an IMT, because ALK gene rearrangement was confirmed by fluorescent in-situ hybridization. Cytoplasmic staining for KIT and the absence of other GIST markers, including DOG1 and platelet-derived growth factor α, indicated that the tumor was not a GIST. Therefore, IMTs should be included in the differential diagnosis of spindle cell tumors, even those that are KIT-positive.

Primary intraocular inflammatory myofibroblastic tumor with anaplastic lymphoma kinase overexpression.

The human eye can be compromised by a variated spectrum of neoplasms and reactive processes. Here we present a rare case of a primary intraocular inflammatory myofibroblastic tumor (IMT) dependent on the sclera and choroid in a 31-year-old female. The knowledge surrounding IMTs, previously included in the category of inflammatory pseudotumors, has undergone dynamic changes in the past two decades. Here we review the characteristics of these tumors in the human eye and in the surrounding structures, and we describe the recent advances that allow molecular characterization of the neoplastic nature of this entity.

[Plexiform angiomyxoid myofibroblastic tumor of stomach].

OBJECTIVE: To study the clinicopathologic features, immunophenotype and differential diagnosis of plexiform angiomyxoid myofibroblastic tumor (PAMT) of the stomach. METHODS: The clinical and pathologic findings of 3 cases of PAMT in the gastric antrum were retrospectively analyzed. Immunohistochemical study was carried out and the literature was reviewed. RESULTS: The age of patients ranged from 31 to 47 years. The male-to-female ratio was 1:2. The clinical presentation included epigastric pain and distension. Endoscopically, the tumor mass protruded into the gastric cavity at the antrum and ranged from 4.5 cm to 8.0 cm in greatest dimension. One of the tumors studied was associated with surface ulceration. Histologically, the tumors were located in the gastric wall. They were composed of bland spindle cells and small vessels arranged in a plexiform or nodular pattern within a myxoid stroma. Immunohistochemical study showed that the spindle cells were consistently positive for smooth muscle actin and muscle-specific actin. There was focal staining for h-caldesmon, desmin in case 3 and focal positive for epithelial membrane antigen, CAM5.2 in case 1. Further, CD10 and progesterone receptor were positive in case 3. CONCLUSIONS: PAMT represents a rare novel mesenchymal tumor of the stomach, with a propensity of gastric antral involvement. The distinctive pathologic features help to differentiate this entity from other benign and malignant tumors.

Dermatomyofibromas presenting in pediatric patients: clinicopathologic characteristics and differential diagnosis.

Dermatomyofibroma represents a rare benign fibroblastic/ myofibroblastic cutaneous tumor that mostly occurs in young adult women. It has been seldom reported in pediatric patients. In this analysis, the clinical, histopathological and immunohistochemical findings of 12 dermatomyofibromas occurring in patients up to 16 years of age are compared with those reported in adults. Six patients were male and six were female. Nine lesions were located on the neck, two on the back and one involved the chest. The usual presentation was as an asymptomatic plaque composed of bland spindled cells arranged in dermal fascicles that were oriented parallel to the epidermis. Immunohistochemically, the lesional cells expressed calponin in 11 cases, smooth muscle actin in six and muscle-specific actin in three. In contrast to prior reports from adults, dermatomyofibromas in pediatric patients do not show a female predilection. In addition, they are mostly located on the neck (56%), while in adults the most frequent location is the shoulder (35%). Dermatomyofibromas seem to stabilize after an initial period of enlargement. Punch biopsy and clinical follow up could be an alternative approach to the surgical excision in some cases of dermatomyofibroma, particularly in instances in which surgery might inflict cosmetic defects.

Cytology of fine-needle aspiration of inflammatory myofibroblastic tumor.

Inflammatory Myofibroblastic Tumor (IMT) is a rare spindle cell neoplasm with a relatively indolent course. Its morphology may be confused with both reactive processes and/or malignant neoplasms on FNA specimens. Herein we discuss the cytologic features and IHC studies of IMT. The archives of the Department of Pathology at the Johns Hopkins Hospital were searched for IMT. A total of 257 cases were identified over a period of 11 years. Among them, 20 cases had cytology material. The patients' ages ranged from 7 to 81 years old with a median age of 54 years. The locations of the tumor in descending order were: liver (9/20, 45%), lung (8/20, 40%), abdomen (1/20, 5%), pelvis (1/20, 5%), and kidney (1/20, 5%). On FNA, the majority of tumors consisted of bland spindle cells with oval nuclei and small prominent nucleoli in a background of lymphocytes and plasma cells. Focal cytological atypia and "ganglion-like" cells were identified in 7 cases, likely related to the risk of metastases and malignant transformation. The lesional cells expressed ALK (8/17, 47.1%) and actin (10/10, 100%), but with variable expression of cytokeratin. Ki-67 showed low proliferative indices. ALK gene rearrangement was detected by FISH in three out of three cases and correlated with ALK protein expression by IHC. The cytologic diagnosis of IMT is challenging. When encountering a spindle cell lesion with prominent inflammatory component, a high index of suspicion in combination with the use of ancillary studies increases the diagnostic yield of IMT.

[Infantile myofibroma and myofibromatosis: clinical and morphologic assessment of eighteen cases].

Infantile myofibroma (myofibromatosis) (IM) is a mesenchymal tumor of soft tissues of the head, extremities and trunk. It is characterized by relapse-free infiltrative growth. It consists of neoplastic myofibroblasts at varying stage of cell differentiation which form multi-structured tumor zones. IM's morphological differentiated diagnosis is established vis-a-vis other varieties of tumor and reactive nodular structures of fibroblasts, primarily, infantile hemangiopericytomas and desmoid fibromatosis. Immunohistological and ultrastructural examination of tumor is required for making correct diagnosis of IM.

Congenital myofibroma of the skin mimicking a piloleiomyoma.

Myofibroma is an uncommon benign soft tissue disorder, which is usually congenital or present in early infancy. Myofibroma usually manifests as a single mass. When there are multiple lesions, the term myofibromatosis is used. The characteristic histopathological feature of the myofibroma is the coexistence of two distinct areas. One area mainly contains plump spindle cells with thin blunt-ended nuclei and eosinophilic cytoplasm, thus indicating myoid characteristics. The other area contains either round or polygonal cells with slightly pleomorphic, hyperchromatic nuclei or small spindle cells typically arranged around a distinct hemangiopericytoma-like vascular pattern. In the present case, the majority of the tumor was composed of the plump myoid spindle cells. This led to an initial diagnosis of a piloleiomyoma. However, the tumor cells were not immunohistochemically positive for desmin. Moreover, careful examination revealed a hemangiopericytoma-like vascular pattern characterized by the presence of high cellular areas with irregular vascular spaces. These features led to the final diagnosis of the myofibroma. It is therefore important to recognize the leiomyoma-like variants of myofibromas.

Inflammatory myofibroblastic tumors in childhood: a report from the Italian Cooperative Group studies.

BACKGROUND: Inflammatory myofibroblastic tumors (IMTs) are myofibroblastic lesions with unpredictable biologic behavior that occur at a young age. For this report, the authors investigated clinicopathologic features in a series of pediatric IMTs. The objective of the study was to identify morphologic or immunohistochemical prognostic markers and the possible pathogenic role of human herpes virus 8 (HHV-8). METHODS: Twenty-six patients were observed over a period of 18 years. Clinical/histologic data were reviewed, and immunohistochemical/molecular studies were performed. RESULTS: Patients ages 8-216 months (median age, 60 months) presented with tumors of the lung-bronchus (8 patients), abdomen (17 patients), and thoracic wall (1 patient). Twenty-one patients underwent complete excision, and microscopic or macroscopic residual disease was present in 5 of those patients. Chemotherapy was received by 5 patients. After a median follow-up of 6.6 years, 24 patients were in complete remission, and 2 patients had died of disease. Local recurrences were observed in 6 patients (including 4 recurrences that occurred after a complete excision). Cytologic atypia, low inflammatory infiltrate, and a rich myxoid pattern were detected in patients who had recurrent disease or a poor prognosis. Anaplastic lymphoma kinase (ALK) was positive in 7 patients (including 2 patients with recurrent disease). No correlation between clusterin expression and prognosis was demonstrated. HHV-8 was identified in 1 pulmonary IMT. CONCLUSIONS: IMTs are locally aggressive lesions. In this series, the local recurrence rate was 23%, and the 5-year and 10-year event-free survival rates were 87.4% and 72.8%, respectively. The results indicated that the treatment of choice is a complete, nonmutilating excision; chemotherapy may be given to patients who have microscopic or macroscopic residual disease, although the results are controversial; cytologic atypia and positive ALK status are more frequent in aggressive tumors, whereas metastatic tumors are negative for ALK; and HHV8 is not involved in the pathogenesis of IMT.

Myofibroma of the external auditory canal: report of an adult case.

UNLABELLED: Myofibroma of the external auditory canal: report of an adult case. OBJECTIVE: Myofibroma is a benign fibrous proliferative disease generally reported to occur in neonates and children. Similar lesions have been reported in adults, but solitary tumours affecting the external auditory canal are extremely rare. Only one such case has been reported in the literature. CASE REPORT: The case of solitary myofibroma occurring in the external auditory canal of a 42-year-old woman is presented. The diagnosis of myofibromatosis was made on the basis of its histological appearance and corroborated by immunohistochemical staining. CONCLUSIONS: Clinicians and pathologists must be aware that myofibromatosis may occur in adults at extremely rare locations. Myofibroma should be included in the differential diagnosis of fibrous lesions in the external auditory canal.