Primary diagnosis of ruptured biceps tendon "Baker's-type cyst" using fine needle aspiration biopsy: A case report

Biceps tendon rupture is generally a clinical and radiographic diagnosis, and only rarely presents to the cytopathologist for fine needle aspiration biopsy. We present a case of ruptured biceps tendon associated with a cystic mass of the upper arm that was diagnosed using fine needle aspiration biopsy, and confirmed with subsequent MRI scan. We describe the clinical presentation, cytomorphology, and immunohistochemical profile of the marked chronic inflammatory infiltrate within the synovial fluid. We also provide a discussion of the differential diagnosis for a cystic mass associated with the biceps tendon on cytology.

Activating BRAF and PIK3CA mutations cooperate to promote anaplastic thyroid carcinogenesis

Thyroid malignancies are the most common type of endocrine tumors. Of the various histologic subtypes, anaplastic thyroid carcinoma (ATC) represents a subset of all cases but is responsible for a significant proportion of thyroid cancer-related mortality. Indeed, ATC is regarded as one of the more aggressive and hard to treat forms of cancer. To date, there is a paucity of relevant model systems to critically evaluate how the signature genetic abnormalities detected in human ATC contribute to disease pathogenesis. Mutational activation of the BRAF protooncogene is detected in approximately 40% of papillary thyroid carcinoma (PTC) and in 25% of ATC. Moreover, in ATC, mutated BRAF is frequently found in combination with gain-of-function mutations in the p110 catalytic subunit of PI3'-Kinase (PIK3CA) or loss-of-function alterations in either the p53 (TP53) or PTEN tumor suppressors. Using mice with conditional, thyrocyte-specific expression of BRAF(V600E), we previously developed a model of PTC. However, as in humans, BRAF(V600E)-induced mouse PTC is indolent and does not lead to rapid development of end-stage disease. Here, we use mice carrying a conditional allele of PIK3CA to demonstrate that, although mutationally activated PIK3CA(H1047R) is unable to drive transformation on its own, when combined with BRAF(V600E) in thyrocytes, this leads to development of lethal ATC in mice. Combined, these data demonstrate that the BRAF(V600E) cooperates with either PIK3CA(H1074R) or with silencing of the tumor-suppressor PTEN, to promote development of anaplastic thyroid carcinoma.

IMPLICATIONS

This genetically relevant mouse model of ATC will be an invaluable platform for preclinical testing of pathway-targeted therapies for the prevention and treatment of thyroid carcinoma.

Diminished WNT -> β-catenin -> c-MYC signaling is a barrier for malignant progression of BRAFV600E-induced lung tumors

Oncogene-induced senescence (OIS) is proposed as a cellular defense mechanism that restrains malignant progression of oncogene-expressing, initiated tumor cells. Consistent with this, expression of BRAF(V600E) in the mouse lung epithelium elicits benign tumors that fail to progress to cancer due to an apparent senescence-like proliferative arrest. Here we demonstrate that nuclear β-catenin → c-MYC signaling is essential for early stage proliferation of BRAF(V600E)-induced lung tumors and is inactivated in the subsequent senescence-like state. Furthermore, either β-catenin silencing or pharmacological blockade of Porcupine, an acyl-transferase essential for WNT ligand secretion and activity, significantly inhibited BRAF(V600E)-initiated lung tumorigenesis. Conversely, sustained activity of β-catenin or c-MYC significantly enhanced BRAF(V600E)-induced lung tumorigenesis and rescued the anti-tumor effects of Porcupine blockade. These data indicate that early stage BRAF(V600E)-induced lung tumors are WNT-dependent and suggest that inactivation of WNT → β-catenin → c-MYC signaling is a trigger for the senescence-like proliferative arrest that constrains the expansion and malignant progression of BRAF(V600E)-initiated lung tumors. Moreover, these data further suggest that the trigger for OIS in initiated BRAF(V600E)-expressing lung tumor cells is not simply a surfeit of signals from oncogenic BRAF but an insufficiency of WNT → β-catenin → c-MYC signaling. These data have implications for understanding how genetic abnormalities cooperate to initiate and promote lung carcinogenesis.

Mutationally activated PIK3CA(H1047R) cooperates with BRAF(V600E) to promote lung cancer progression

Adenocarcinoma of the lung, a leading cause of cancer death, frequently displays mutational activation of the KRAS proto-oncogene but, unlike lung cancers expressing mutated EGFR, ROS1, or ALK, there is no pathway-targeted therapy for patients with KRAS-mutated lung cancer. In preclinical models, expression of oncogenic KRAS(G12D) in the lung epithelium of adult mice initiates development of lung adenocarcinoma through activation of downstream signaling pathways. In contrast, mutationally activated BRAF(V600E), a KRAS effector, fails to initiate lung carcinogenesis despite highly efficient induction of benign lung tumorigenesis. To test if phosphoinositide 3-kinase (PI3K)-α (PIK3CA), another KRAS effector, might cooperate with oncogenic BRAF(V600E) to promote lung cancer progression, we used mice carrying a conditional allele of Pik3ca that allows conversion of the wild-type catalytic subunit of PIK3CA to mutationally activated PIK3CA(H1047R). Although expression of PIK3CA(H1047R) in the lung epithelium, either alone or in combination with PTEN silencing, was without phenotype, concomitant expression of BRAF(V600E) and PIK3CA(H1047R) led to dramatically decreased tumor latency and increased tumor burden compared with BRAF(V600E) alone. Most notably, coexpression of BRAF(V600E) and PIK3CA(H1047R) elicited lung adenocarcinomas in a manner reminiscent of the effects of KRAS(G12D). These data emphasize a role for PI3K signaling, not in lung tumor initiation per se, but in both the rate of tumor growth and the propensity of benign lung tumors to progress to a malignant phenotype. Finally, biologic and biochemical analysis of BRAF(V600E)/PIK3CA(H1047R)-expressing mouse lung cancer cells revealed mechanistic clues about cooperative regulation of the cell-division cycle and apoptosis by these oncogenes.

Mutationally activated BRAF(V600E) elicits papillary thyroid cancer in the adult mouse

Mutated BRAF is detected in approximately 45% of papillary thyroid carcinomas (PTC). To model PTC, we bred mice with adult-onset, thyrocyte-specific expression of BRAF(V600E). One month following BRAF(V600E) expression, mice displayed increased thyroid size, widespread alterations in thyroid architecture, and dramatic hypothyroidism. Over 1 year, without any deliberate manipulation of tumor suppressor genes, all mice developed PTC displaying nuclear atypia and marker expression characteristic of the human disease. Pharmacologic inhibition of MEK1/2 led to decreased thyroid size, restoration of thyroid form and function, and inhibition of tumorigenesis. Mice with BRAF(V600E)-induced PTC will provide an excellent system to study thyroid tumor initiation and progression and the evaluation of inhibitors of oncogenic BRAF signaling.

Reproducibility of colon tumor grade and relationship to recurrence in the context of clinical, pathologic, and genomic tumor features in 504 patients with stage II colon cancer treated with surgery alone at the Cleveland Clinic

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Background: High tumor grade is included in practice guidelines as a marker of higher recurrence risk in stage II colon cancer. Multiple systems for tumor grading exist, without a standardized approach. We characterize agreement of 2 methods for tumor grading and association with recurrence in the context of clinical, pathologic, and genomic tumor features including mismatch repair (MMR) and the 12-gene recurrence score (RS).

Methods: Colon tumors were graded independently by 2 academic GI pathologists (P1, P2). Grade was defined by % tumor with gland-like structures: well (> 95%), moderately (50-95%) and poorly (< 50%) differentiated. P1 used this 3-tier system while P2 used 2-tier scheme with well and moderately differentiated tumors defined as low grade and poorly differentiated as high grade. All mucinous tumors were high-grade by P2 but not P1. Relationship to recurrence-free interval (RFI) was assessed by Cox regression.

Results: Primary tumors from 504 stage II colon cancer treated with surgery alone were included. 18% (P1) and 31% (P2) were high grade. High grade tumors were more likely right-sided (≥ 60%) and MMR deficient (≥ 35%) for P1 and P2 (all p < 0.001). Proportion of mucinous tumors was similar for high and low grade by P1 (25% vs. 21%, p = 0.39). P2 high grade trended to lower recurrence (HR = 0.63, p = 0.10) while P1 grade was not associated w/ RFI (p = 0.46). In multivariate analyses including grade and RS, P2 high grade was associated with lower recurrence (p = 0.007) but P1 grade was not associated w/ RFI (p = 0.30). Neither grade was associated w/ RFI (p > 0.30) after controlling for RS, MMR, tumor location and mucinous histology. Using the two-tier scheme, agreement b/w the 2 pathologists was low (kappa = 0.30, 95% CI 0.21-0.39) in all pts and moderate if mucinous tumors were excluded (kappa = 0.52, 95% CI 0.40-0.64).

Conclusions: High tumor grade was not found to be a marker of higher recurrence risk in stage II colon cancer. Other markers validated in stage II colon cancer, such as MMR and RS, should be considered. Interpathologist agreement on colon tumor grade is modest, even with central expert review.

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Homeodomain transcription factor NKX2.2 functions in immature cells to control enteroendocrine differentiation and is expressed in gastrointestinal neuroendocrine tumors

The homeodomain transcription factor NKX2.2 is necessary for neuroendocrine (NE) differentiation in the central nervous system and pancreas. NE tumors derived from the gut are defined by their NE phenotype, which is used for diagnosis and contributes to tumorigenicity. We hypothesized that NKX2.2 is important for NE differentiation in normal and neoplastic gut. NKX2.2 and NE marker expression was investigated in the small intestine of embryonic and adult mice using immunofluorescence (IF). To determine the role of NKX2.2 in NE differentiation of the intestine, the phenotype of Nkx2.2 (-/-) mice was examined by IF and real-time (RT)-PCR. NKX2.2 and NE marker expression in human NE tumors of the gut and normal tissues were evaluated by immunohistochemistry and qRT-PCR. NKX2.2 expression was detected in the intervillus/crypt regions of embryonic and adult mouse intestine. Co-expression of Nkx2.2 with neurogenin3 (NEUROG3) and hormones was observed in the adult intestinal crypt compartment, suggesting NKX2.2 functions in NEUROG3-positive endocrine progenitors and newly differentiated endocrine cells. In the intestine of Nkx2.2 (-/-) mice, we found a dramatic reduction in the number of cells producing numerous hormones, such as serotonin, gastrin, cholecystokinin, somatostatin, glucagon-like peptide 1 (GLP-1), and secretin, but an increase in cells producing ghrelin. NKX2.2 was expressed in most (24 of 29) human NE tumors derived from diverse primary sites. We conclude NKX2.2 functions in immature endocrine cells to control NE differentiation in normal intestine and is expressed in most NE tumors of the gut, and is therefore a novel target of diagnosis for patients with gastrointestinal NE tumors.

Report of a hürthle cell neoplasm in a peripubertal girl

Thyroid nodules are rare in children compared to adults. Although most thyroid nodules are benign, the risk of malignancy is greater in pediatric patients. Papillary and follicular cell tumors account for the majority of thyroid neoplasms; Hürthle cell tumors account for less than 5%. Despite being uncommon, malignant Hürthle cell tumors are potentially more aggressive than papillary and follicular cell tumors. Therefore, distinguishing between types of thyroid neoplasms in a timely fashion has implications for prognosis and therapy. We describe a 12-year-old peripubertal girl who presented with a large right-sided thyroid nodule that was subsequently diagnosed as a Hürthle cell adenoma. To our knowledge, she represents the youngest patient with a Hürthle cell neoplasm.

Solitary fibrous tumor of the retropharynx causing obstructive sleep apnea

Solitary fibrous tumors (SFTs) are rare, usually benign, spindle cell neoplasms that most often originate near mesothelium-lined surfaces of the pleural or peritoneal cavity. SFTs reported in the head and neck occur most commonly in the oral cavity, sinonasal tract, and orbit. We report a case of SFT of the retropharynx causing severe obstructive sleep apnea. The diagnostic and management strategies of SFTs are discussed.

June 2003: 33-year-old male with a frontal lobe mass

The June 2003 COM. A 33-year-old male with a history of seizures was found to have an intra- and extra-axial frontal lobe mass. The histology of the resected tumor showed a meningioma with underlying meningioangiomatosis. Meningioangiomatosis (MA) is a benign intracortical plaque-like proliferation of meningothelial cells, microvasculature and fibroblast-like cells probably of hamartomatous origin. Very rarely, MA is associated with an overlying meningioma as in this case. When MA is accompanied by a meningioma, it is generally not associated with clinical evidence of neurofibromatosis. It is important to distinguish MA from an invasive meningioma, because of its favorable prognosis after resection.

Macrophage trafficking in the uterus and cervix precedes parturition in the mouse

Immune activation is implicated in the etiology of preterm labor, but little is known about macrophage number or distribution in the uterus or cervix at term. This study tested the hypothesis that macrophages migrate into the reproductive tract before the onset of parturition. Paraffin-embedded sections from the mid-uterine horn and cervix of C3/HeN mice on Days 15 and 18 of pregnancy, the day of birth (Day 19), and 1 day postpartum were stained with a pan-macrophage marker to analyze cell numbers and distribution. During pregnancy, uterine macrophages were dispersed in endometrium, usually associated with vasculature and subluminal epithelium. In myometrium, macrophages were clustered in stromal connective tissue; near term and postpartum, cells appeared to surround the muscle bundles. Total macrophage numbers were increased on Day 15 relative to those in nonpregnant controls, declined before birth, and increased postpartum. In the cervix, macrophages congregated in subepithelium, often perivascular or near ganglia. Macrophage numbers in the cervix peaked on Day 18, then declined to nonpregnant levels by the day after birth. Thus, macrophage numbers in the uterus were inversely related to those in the cervix. These findings raise the possibility that macrophages and their products may be involved in uterine contractility and cervical remodeling during the processes of parturition.