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Introduction: Exosomes have pivotal roles in cancer development. The impact of neoadjuvant concurrent chemoradiation (NCCR) on exosomal markers (CD63 and CD9) expression and their prognostic significance in patients with rectal adenocarcinoma are yet to be explored. Materials and Methods: Between 2015 and 2018, 33 patients had rectal adenocarcinoma treated with NCCR and had pre-NCCR biopsy and post-NCCR resected rectum. CD63 and CD9 expression was assessed by immunohistochemistry (IHC). The short-term surrogate endpoint neoadjuvant rectal (NAR) score was used for assessment of prognostic significance. Un-Paired t-test was used for statistical analysis. Results: The mean tumor CD63 and CD9 scores in pre-NCCR biopsy vs. post-NCCR resected rectum were 106 vs. 165 (P = 0.0022) and 136 vs. 215 (P < 0.0001) respectively. The mean tumor CD63 and CD9 scores respectively in pre-NCCR biopsy was 99 and 130 in patients with low-intermediate NAR score compared to 117 and 144 in patients with high NAR score (P = 0.4934) (P = 0.5519). The mean tumor CD63 and CD9 scores respectively in post-NCCR resected rectum was 155 and 205 in patients with low-intermediate NAR score compared to 180 and 230 in patients with high NAR score (P = 0.3793) (P = 0.2837). Conclusions: The expression of the exosomal markers (CD63 and CD9) increased in patients with rectal adenocarcinoma after treatment with NCCR. The exosomal markers (CD63 and CD9) may have a prognostic significance. There was a trend for higher CD63 and CD9 expression in patients with high NAR score compared with low-intermediate NAR scores. The lack of statistical significance is likely due to the small sample size.

Introduction/Objective Most low-grade B-cell lymphomas of the thyroid are extranodal marginal cell lymphomas (MZL) and may exhibit focal plasma cell differentiation (PCD). PCD could occasionally be extensive, mimicking a true plasma cell neoplasm (PCN). PCN of the thyroid are extremely rare, representing either a component of plasma cell myeloma (PCM), or a primary thyroid extraosseous plasmacytoma (EOPC). We present a case of primary thyroid plasma cell (PC)-rich neoplasm with considerable diagnostic challenge. Methods A 46-year-old male underwent total thyroidectomy for hypothyroidism and compressive symptoms. Microscopically, sheets and nodules of PC with focal plasmablastic features were demonstrated in a background of fibrosing chronic thyroiditis. One benign perithyroidal lymph node was seen. The differential diagnosis included B-cell neoplasm with extensive PCD (ie, MZL or lymphoplasmacytic lymphoma) and PCN. Results Immunohistochemically, the PCs were positive for CD79a, MUM1, BCL2 and IgM with Kappa light-chain restriction and partial CD138 expression, and negative for CD20, PAX5, HHV8, Cyclin-D1, SOX11, CD117 and IgG. EBER was negative. Rare reactive-appearing B-cell aggregates with associated T-cells were noted. FISH for API/MALT1-fusion t(11;18) and PCR for MYD-88 mutation were negative. However, polysomy 18 (seen in 15–33% of B-cell lymphomas, including MZL) was detected. Serum proteins and PCM workup were negative. The findings were consistent with primary thyroid Kappa-restricted PC-rich neoplasm. While the absence of detectable B-cell neoplastic component was suggestive of EOPC, the diagnosis of MZL with extensive PCD was favored due to the thyroid involvement in a background of thyroiditis, absence of lymph node involvement, detection of polysomy 18, and absence of MYD-88. Follow-up of the patient was thought to be most reasonable. Conclusion Plasma cell-rich hematolymphoid neoplasms of the thyroid may cause a considerable diagnostic challenge. Differentiating between B-cell lymphomas with extensive PCD and PCN may be difficult or even impossible by morphology alone. Additional ancillary tests may be necessary.

101 Background: Exosomes mediate intercellular communications and have pivotal roles in cancer development. CD63 and CD9 are widely accepted exosomal markers. The effect of concurrent chemoradiation on the expression of exosomal markers is unknown. Here we explored the effect of neoadjuvant concurrent chemoradiation (NCCR) on exosomal markers (CD63 and CD9) expression in patients with locally advanced rectal cancer (LARC). Methods: Between 2015 and 2018, 33 patients had LARC treated with NCCR and had pre NCCR biopsy and post NCCR resected rectum examined for exosomal markers expression using immunohistochemistry. Two pathologists independently scored CD63 and CD9 staining in the tumor. Staining intensity was graded from 1-3. Staining percentage was estimated in 10% increments. Mean quick-score (Q-score) was calculated (intensity x percentage). Un-Paired t test was used for statistical analysis. Results: In our cohort, median age was 59 years. Males represented 79% of the patients. Caucasians, African American and other ethnic groups represented 70%, 27% and 3% respectively.The mean tumor CD63 score in pre NCCR biopsy vs post NCCR resected rectum was 106 vs 165 (p = 0.0022). The mean tumor CD9 score in pre NCCR biopsy vs post NCCR resected rectum was 136 vs 215 (p < 0.0001). The exosomal markers expression in the adjacent normal mucosa (ANM) from pre NCCR biopsy and post NCCR resected rectum was only performed in16 out of 33 patients (due to ANM tissue availability). The mean ANM CD63 score in pre NCCR biopsy vs post NCCR resected rectum was 166 vs 183 (p = 0.37). The mean ANM CD9 score in pre NCCR biopsy vs post NCCR resected rectum was 104 vs 145 (p = 0.0897). Conclusions: In patients with LARC, the expression of exosomal markers (CD63 and CD9) increased after treatment with NCCR. Our results show that the expression of CD63 and CD9 is relatively higher in rectal cancer specimens treated with NCCR and thus suggest a possible role of these exosomes in adaptive response to NCCR. Further follow-up and laboratory studies are required to precisely understand the underlying mechanism(s).

Objectives Dysembryoplastic neuroepithelial tumor (DNET) is an uncommon mixed glioneuronal tumor. DNET is classified as WHO grade I neoplasm and commonly seen in the temporal lobe of children and young adults with features of pharmacoresistant seizures. The term complex DNET defines those tumors associated with additional features, including a pilocytic astrocytoma (PA) component, a finding that is rarely described in the literature. Methods Here we report a 16-year-old male who presented with seizures. On imaging, a 5.5 × 2.2 × 2.1-cm multiloculated mass was centered in the left frontoparietal gray matter with solid and cystic components and focal areas of contrast enhancement. Results Microscopic examination revealed a noninfiltrative glioneuronal neoplasm composed of a bland population of round to oval cells arranged around pools of mucinous material. Occasional large neuronal cells were noted. Focal areas composed of elongated astrocytic cells demonstrating piloid morphology were also present. No high-grade features were demonstrated. The findings are consistent with DNET, complex form in addition to a second component with piloid features resembling pilocytic astrocytoma. Conclusion The early recognition of DNET is important as it has an excellent prognosis on complete surgical excision without use of adjunct therapies. Unresected or incompletely removed DNET and secondary radiochemotherapy may give rise to recurrence and malignancy. The development of the secondary neoplasm challenges the stability in terms of biological behavior and highlights the importance of complete surgical excision and close follow-up. Our patient had neither undergone previous surgery nor received any adjuvant therapy, and hence this case is a de novo development of PA in a DNET. The association of contrast enhancement with DNET is an unusual finding in this case.

Objective Primary sarcomas of the vulva are very rare malignancies, accounting for 1% to 3% of all gynecologic sarcomas. Leiomyosarcoma is the most common histologic type. They present with nonspecific symptoms, aggressive behavior, and high metastatic potential. Methods A 63-year-old female patient presented with a 6-month history of a slow-growing, painless vulvar mass at the right posterior fourchette. CT scan revealed an asymmetric, heterogeneous vulvar mass extending to the distal vagina, without lymphadenopathy or evidence of distant metastasis. Focal prominence of the uterus suggestive of leiomyoma was also noted, but primary uterine neoplasm with vulvar metastasis could not be excluded. The patient underwent wide local excision of the vulvar mass with hysterectomy and bilateral salpingo-oophorectomy. Results Gross examination of the vulvar specimen showed an ulcerated 2.1-cm solid white mass with irregular borders. Microscopically, the vulvar tumor consisted of a focally infiltrative spindle and pleomorphic neoplastic proliferation with interlacing fascicular pattern and increased mitotic activity up to 25/10 HPF, without necrosis or lymphovascular invasion. The tumor focally extended to resection margins. Immunohistochemically, the neoplastic cells were positive for SMA, ER, and desmin and negative for S-100 and cytokeratin AE1/AE3. These findings, in conjunction with the clinical presentation, were consistent with high-grade primary vulvar leiomyosarcoma. Radiation therapy was subsequently started. Conclusion Primary vulvar leiomyosarcomas are rare and secondary involvement by uterine primary should always be ruled out. In addition, these tumors can be mistaken clinically as benign processes such as Bartholin gland cysts, infectious granuloma, fibroma, or myoma. Hence, it is vital to consider vulvar sarcomas in the differential diagnosis of nonspecific vulvar lesions in order to avoid delay in diagnosis and treatment. The rarity of this diagnosis makes this case worth reporting.

Skeletal muscle involvement by noncaseating granulomata occurs in a variety of conditions, including sarcoidosis, infections, and rarely in association with primary inflammatory myopathies such as inclusion body myositis (IBM) and dermatomyositis (DM). Sarcoid myopathy is typically asymptomatic; however, a picture of acute myositis with proximal muscle weakness has been described. Immune-mediated necrotizing myopathy (IMNM) is a subgroup of inflammatory myopathies typically presenting with proximal muscle weakness and markedly elevated muscle enzymes, mostly occurring in the setting of statin treatment. IMNM is associated with positive autoantibodies, but a subset of cases is antibody negative. Here we describe a case of myopathy occurring in association with sarcoidosis with combined features of granulomatous and necrotizing myopathy. The patient was a 54-year-old African American male with medical history significant for statin use 3 years ago, which was discontinued due to myalgia and elevated muscle enzymes and biopsy-proven sarcoidosis diagnosed on a pulmonary lymph node biopsy. He presented with progressive worsening of bilateral proximal weakness involving the upper and lower extremities. Electromyogram showed features of active myopathy with no evidence of peripheral neuropathy. Myositis panel was negative for the following antibodies: anti-Jo1, Mi-2, anti-Ku, PL-7, PL-12, OJ, EJ, and SRP. However, there was elevation of aldolase, CRP, and CK-MB. Biopsy of thigh and deltoid muscle showed necrotic muscle fibers, myophagocytosis with associated minimal inflammation, and multiple well-formed nonnecrotizing granulomas with multinucleated giant cells. Myopathic features include increased internalized nuclei, round atrophic fibers, and scattered split fibers. Specific features of IBM or DM were not present. Conclusion Myopathies developing or worsening after discontinuation of statin are rare. The association of necrotizing myopathy with sarcoidosis is not well described in the literature. Additional studies are warranted to elucidate this association.