Proposal to Eliminate Urethane-Treated Positive Control Dose Groups in 26-Week Tg.rasH2 Carcinogenicity Studies.

Short-term (26 weeks) Tg.rasH2 mouse carcinogenicity studies have been conducted as an alternative model to the conventional 2-year mouse carcinogenicity studies, using urethane as a positive control material. In these studies, urethane was used at a dose of 1,000 mg/kg/dose, administered intraperitoneally on days 1, 3, and 5. Urethane consistently produces lung adenomas and carcinomas and hemangiosarcomas of the spleen, proving validity of the assay. We conducted 3 pilot studies at 3 different sites of Charles River Laboratories using a lower dose of urethane (500 mg/kg/dose), administered on days 1, 3, and 5, followed by a 12-week observation period. Our results demonstrate that a lower dose can be used successfully with fewer number of animals per sex to prove the validity of the assay. However, based on our cumulative experience with this model, we propose to eliminate positive control dose groups in future Tg.rasH2 carcinogenicity studies.

Metástasis solitaria intraparenquimatosa del bazo estudios clínicos patológicos e inmunohistoquímico / Intraparenchymal solitary spleen metastasis pathological and immunohistochemical clinical studies

Las metástasis esplénicas intra-parenquimatosas de tumores sólidos son tumores muy raros, y si se trata de nódulos únicos, son excepcionales. Presentamos dos casos de metástasis intra-parenquimatosas. El primer caso se trató de una mujer de 66 años con antecedentes de un adenocarcinoma endometrial. El segundo caso se trató de un paciente de sexo masculino con antecedente de un adenocarcinoma prostático, quien se presentó con un adenocarcinoma mucinoso en el bazo, como segunda neoplasia. También realizamos una revisión de los registros de biopsias de 14 años, del servicio de anatomía patológica del instituto(AU)

The spleen parenchymal metastasis of the solid tumors, are very rare, but the isolated metastasis to the spleen are considered exceptional. We herein present two cases of the isolated splenic metastases. The first case was a female a 66 year old female with a diagnosis endometrial adenocarcinoma. The second cases was a 71 years old male, with a history of a prostatic adenocarcinoma, and a spleen metastasis of a ucinous adenocarcinoma, as a second malignancy. We also made a review of 14 years, biopsies records from the pathology service, of the institute(AU)

Protective mechanisms of purified polyphenols from pinecones of Pinus koraiensis on spleen tissues in tumor-bearing S180 mice in vivo.

The previous study evaluated the antitumor activity and the underlying mechanism of the purified polyphenols from pinecones of Pinus koraiensis (PPP-40) using a tumor-bearing S180 mice model. This study was designed to evaluate the protective effects of PPP-40 on spleen tissues of S180 mice in vivo. Pretreatment with PPP-40 (150 mg per kg BW per D) could significantly inhibit tumor growth, enhance spleen index and prevent the decline of haematological parameters of S180 mice induced by the tumor microenvironment. Moreover, the treatment with PPP-40 was shown to significantly inhibit splenocyte apoptosis by TUNEL staining and flow cytometry, characterized by the inhibition of splenocyte cycle (G0/G1) arrest, increase in the percentages of splenic T lymphocytes (CD3+ T cells) and T cell subsets (CD3+CD4+ and CD3+CD8+ T cells), as well as the production of T cell-related cytokines (IL-2, IL-12, and TNF-α) in splenocytes exposed to the tumor microenvironment. These effects were associated with a decrease in oxidative stress, as evidenced by the changes in the SOD, GSH-Px, GSH and MDA levels of liver and spleen tissues of S180 mice. Furthermore, the protective effect of PPP-40 on spleen tissues was deeply analyzed by detecting apoptosis-related proteins using immunohistochemistry staining. The results indicated that the protective multi-mechanisms of action also were associated with the inhibition of apoptosis through down-regulation protein expressions of Bax, caspase-9, caspase-8 caspase-3, Fas and up-regulation of the expressions of Bcl-2. These results suggested that PPP-40 is a natural antitumor agent and possesses strong immunomodulatory activities by protecting the spleen tissues of tumor-bearing S180 mice.

Dynamics of the spleen and its significance in a murine H22 orthotopic hepatoma model.

The dynamics of the spleen during tumor progression remains incompletely understood. In this study, we established a murine H22 orthotopic hepatoma model and dynamically detected alterations in the percentages of immunocytes in the spleen. We observed a prominent myeloid-derived suppressor cell (MDSC) accumulation during the early response which persisted through all the stages of tumor growth. In addition, the percentage of regulatory T cells (Tregs) increased by week 2. Although the percentage of CD3(+)CD49b(+) natural killer T (NKT) cells increased by day 3, and that of CD3(+)CD4(+) T cells slightly increased by week 1, they decreased to either normal or lower levels compared with those of normal mice. The percentages of total CD3(+), CD3(+)CD4(+), and CD3(+)CD8(+) T cells decreased by week 2, and that of NK cells decreased by week 3. The activation of non-Treg CD4(+) T cells was scarce. Moreover, splenic MDSCs of tumor-bearing mice suppressed the activation of splenocytes. Therefore, a negative immune response gradually prevailed over a positive immune response during tumor growth. In addition, splenectomy was performed at the time of tumor inoculation, and we found that splenectomy could prolong the survival time, reduce the tumor weights, decrease the ascites volumes, and ameliorate the immune status of the tumor-bearing mice. Splenectomy also decreased the percentage of MDSCs and increased the percentages of CD8(+) T cells, NK, and NKT cells in tumor tissues. Additionally, splenectomy decreased the percentage of MDSCs and increased that of CD8(+) T cells in peripheral blood. Overall, our findings suggest that immune-negative cells are dominant in the spleen during tumor progression. Splenectomy could be helpful to improve the immune responses of tumor-bearing hosts.

gga-miR-26a targets NEK6 and suppresses Marek's disease lymphoma cell proliferation.

MicroRNA (miRNA) are a class of highly conserved, small noncoding RNA that emerge as key posttranscriptional regulators in various neoplastic transformations. Our previous study profiling the miRNA transcriptome in Marek's disease virus (MDV)-induced lymphoma revealed many novel and differentially expressed miRNA, including gga-miR-26a, which was downregulated in MDV-infected spleens of chickens. In this study, differential expression of gga-miR-26a between MDV-infected and noninfected spleens at 4, 7, 14, 21, and 28 d postinfection was analyzed by real-time PCR. The results showed gga-miR-26a were downregulated in MDV-infected spleens at cytolytic infection, latency, and tumor transformation phases. Subsequent cell proliferation assay revealed cell viability was lower in gga-miR-26a mimic transfection group than that in negative controls. Target genes of gga-miR-26a were identified by luciferase reporter gene assay. The results showed significant interaction between gga-miR-26a and Never In Mitosis Gene A (NIMA)-related kinase 6 (NEK6) gene. Subsequent gain of function experiment and Western blot assay showed that mRNA and protein levels of NEK6 were downregulated after gga-miR-26 mimic was transfected into MDV-transformed lymphoid cell line (MSB-1), indicating that NEK6 was modulated by gga-miR-26a. The expression of NEK6 showed a higher trend in MDV-infected samples including tumorous spleen and MD lymphoma from liver than that in noninfected controls. The results suggested that gga-miR-26a inhibited MSB-1 cell proliferation. Gga-miR-26a and its direct target, NEK6, might play important roles in MDV infection.

[Solid solitary hamartoma of the spleen].

INTRODUCTION: Hamartoma of the spleen is a rare, sometimes asymptomatic similar to hemangioma benign tumor of the spleen, which, owing to the new diagnostic imaging methods, is discovered with increasing frequency. It appears as solitary or multiple tumorous lesions. CASE OUTLINE: We present a 48-year-old woman in whom, during the investigation for Helicobacter pylori gastric infection and rectal bleeding, with ultrasonography, a mass 6.5x6.5 cm in diameter was discovered by chance within the spleen. Splenectomy was performed due to suspected lymphoma of the spleen. On histology, tumor showed to be of mixed cellular structure, with areas without white pulp, at places with marked dilatation of sinusoids and capillaries to the formation of "blood lakes" between which broad hypercellular Billroth's zones were present. Extramedullary hematopoiesis was found focally. The cells that covered vascular spaces were CD34+ and CD31+ and CD8- and CD21-. CONCLUSION: Hamartoma has to be taken into consideration always when well circumscribed hypervascular tumor within the spleen is found, particularly in children. Although the diagnosis of hamartoma may be suspected preoperatively, the exact diagnosis is established based on histological and immunohystochemistry examinations. Treatment is most often splenectomy and rarely a partial splenectomy is possible, which is recommended particularly in children.

Primary hepatic and hepatosplenic diffuse large B-cell lymphomas with intrasinusoidal and interstitial lymphomatous infiltration.

Primary hepatic and hepatosplenic diffuse large B-cell lymphomas (DLBCLs) are rare cancers and form nodules in most instances. However, very rare cases can diffusely infiltrate the whole liver without nodules. The general clinicopathological features of these lymphomas have not been reported to date. In our current study, we attempted to elucidate the features of these lesions through our direct observations and by reviewing the current literature. We describe the characteristics of 2 patients with hepatic and hepatosplenic DLBCL by autopsy. The lymphoma cells showed diffuse infiltration of the liver, red pulp of the spleen, and bone marrow with intrasinusoidal and interstitial lymphomatous infiltration of the organs. We discuss our observations in relation to previously reported DLBCLs with a similar pathology.

Endoscopic ultrasound guided fine-needle aspiration of a splenic hemangioma with extramedullary hematopoiesis.

Extramedullary hematopoiesis (EMH) is the production of mature blood elements outside of the bone marrow and can occur as a compensatory result of a marrow replacing process or from marrow space occupying lesions such as tumor or marrow fibrosis. EMH can also be induced by factors elicited by neoplasms, such as vascular endothelial growth factor (VEGF). Usually, EMH is a diffuse process most commonly observed in lymph nodes, liver, and spleen. Rarely, EMH can form a mass lesion. Although the spleen is a common site for diffuse EMH, it is a rare location for a mass forming EMH. Hemangiomas are the most common benign tumors of the spleen. A case of a discrete, 8 cm lesion was noted incidentally on CT scan in a 59-year-old man with no significant past medical history. Endoscopic ultrasound guided fine-needle aspiration (EUS FNA) biopsy was performed and cytologic examination revealed trilinear hematopoiesis, with the most distinctive elements being megakaryocytes and erythroid precursors. A diagnosis of EMH was made. On resection, the mass was a hemangioma with EMH. EUS guided FNA is a useful tool for diagnosing splenic masses. Awareness of EMH, both as a mass forming lesion and a feature associated with benign and malignant vascular lesions is important, especially in patients with hematologic malignancies or marrow replacing processes.

Extramedullary hemopoiesis and littoral cell angioma of the spleen: our experience and review.

Littoral cell angioma (LCA) is a rare primary vascular neoplasm of the spleen. A 54-year-old man was referred to our emergency department for abdominal pain. A CT scan showed multiple round hypodense lesions of various sizes throughout the spleen. The spleen was increased in volume. An MRI confirmed the lesion with a suspect of multiple angiomas vs. amartomas. The haematologists excluded any haematological disease. After a collegial discussion, we decided to perform laparotomic splenectomy. Histologically, the multiple lesions consisted in anastomosing vascular channels lined by plump cells. There was an increased number of dysmorphic megakaryocites inside the splenic parenchyma and along the tumour's border, known signs of extramedullary hemopoiesis, whose etiology in our patient was unexplained. To the best of our knowledge this is the third description of the association between littoral cell angioma and extramedullary hemopoiesis. LCA is a rare primary splenic vascular tumour that originates from the splenic littoral cells. The diagnosis of littoral cell angioma is confirmed histologically and on immunohistochemistry. This case report underlines the rarity of this type of benign splenic neoplams, but since the malignant potential of LCA, we recommend close clinical follow- up of patients with LCA of the spleen.

Why the spleen is a very rare site for metastases from epithelial cancers.

It is not known why metastases from epithelial cancers are rare in the spleen, yet common in the other major organs of the reticuloendothelial system in which, like the spleen, leucocytes display a prolonged physiological intravascular transit time. Another unresolved issue that at first seems unrelated to splenic metastases is the inconsistency between the concept of physiological granulocyte disposal through granulocyte ageing and the observation that granulocytes leave the blood in an exponential fashion (half-time 7 h), which implies random disposal. Intravascular granulocytes pass through the spleen with an exponential distribution of transit times (mean 10 min). The spleen is highly active in physiological granulocyte destruction so it is suggested that the variation in times of exposure to the splenic microenvironment converts the age-dependent granulocyte destruction observed ex vivo into the random process observed in vivo, probably through exposure to apoptosis-inducing signals. This leads to the second hypothesis, which is that cancer cells fail to survive in the spleen as a result of these pro-apoptotic signals.

[Inflammatory pseudotumor-like follicular dendritic cell tumor of spleen].

OBJECTIVE: To study the clinicopathologic features of inflammatory pseudotumor-like follicular dendritic cell tumor of spleen. METHODS: One case of inflammatory pseudotumor-like follicular dendritic cell tumor of spleen was examined macroscopically and microscopically. Immunohistochemical study for CD21, CD23, CD35, clusterin, S-100 protein, vimentin, smooth muscle actin, CD1a, CD68, ALK protein, CD30, CD31, CD34, CD3 and CD20 was performed on formalin-fixed, paraffin-embedded sections by standard EnVision method. In-situ hybridization for Epstein-Barr virus (EBV)-encoded RNA was also carried out. RESULTS: Macroscopically, inflammatory pseudotumor-like follicular dendritic cell tumor was large in size, tan-colored, soft to rubbery in consistance and associated with central hemorrhage and necrosis. Histological examination showed scattered follicular dendritic cells admixed with abundant lymphocytes and plasma cells in the background, simulating inflammatory pseudotumor. On high-power magnification, the follicular dendritic cells possessed a moderate amount of pale to lightly eosinophilic cytoplasm, with indistinct cell borders. The nuclei were ovoid or spindly, with vesicular or stippled chromatin and small distinct, often centrally located, nucleoli. Some of the tumor cells showed nuclear pleomorphism and contained irregular foldings of nuclear membrane, coarse chromatin and prominent eosinophilic nucleoli. Mitotic figures were rarely identified. Immunohistochemical study showed that the tumor cells were positive for vimentin, clusterin, smooth muscle actin and CD68. They were weakly and focally positive for CD35 and S-100 protein, but negative for CD21, CD23, CD1a, ALK protein, CD30, CD31 and CD34. Most of the background lymphocytes were of T-lineage (CD3-positive) ,some were CD20 (B-cell marker)-positive. EBV RNA was demonstrated in the tumor cells by in-situ hybridization analysis. CONCLUSIONS: Inflammatory pseudotumor-like follicular dendritic cell tumor is a rarely encountered low-grade malignancy with distinctive morphologic pattern. It is associated with EBV infection.

Splenic marginal zone lymphomas are characterized by loss of interstitial regions of chromosome 7q, 7q31.32 and 7q36.2 that include the protection of telomere 1 (POT1) and sonic hedgehog (SHH) genes.

To further characterize the genotypic features of splenic (S) and nodal (N) marginal zone lymphomas (MZL) we compared eight SMZL and five NMZL by array-based comparative genomic hybridization (aCGH). Arbitrarily, aberrations were divided into major imbalances, defined as gains or losses involving five or more contiguous genetic loci, and minor imbalances, defined as those involving four or fewer loci. SMZL, but not NMZL, demonstrated major imbalances. These included deletions involving various lengths of 7q (three cases), and 14q23q24 (one case) and gains of 9p13p21 (one case), 13q21q33 (one case) and 16p13.1 (one case). Common minor imbalances in SMZL were: loss of sonic hedgehog gene (SHH) at 7q36.2 (four cases), loss of protection of telomere 1 gene (POT1) at 7q31.32 (three cases), and gain of glioma associated oncogene 1 (GLI1) at 12q13.2 (three cases). Common minor alterations in NMZL were: loss of the fas-associated via death domain gene (FADD) at 11q13.2 (three cases) and gain of GLI1 (five cases). In conclusion, SMZL, but not NMZL, demonstrates large genomic imbalances and frequent loss of the 7q31.32 and 7q36.2 regions involving POT1 and SHH, respectively. In NMZL, loss of FADD and gain of GLI1 are frequent events.

Rare T-cell lymphomas.

The evolving classification systems in lymphoma have been driven by advances in the pathologic characterization of lymphoid malignancies. As evidenced by the detailed pathology descriptions earlier, subdividing heterogenous diseases results in an increasing number of distinct subtypes. This has allowed pathologists to provide more accurate diagnoses and begin to shed light on the molecular mechanisms that underlie these disorders. However, clinical information on these rare subtypes has lagged. Standard staging studies are less useful for these primarily extranodal diseases, although newer technologies such as PET scanning might be useful in detecting and following sites of disease. Optimal management remains undefined. Although these lymphomas are often aggressive, particularly in the case of ETCL, HSTCL, and GD-TCL, standard combination-chemotherapy regimens have only rarely provided durable remissions. Highdose therapy strategies have shown early promise, particularly for HSTCL, although conclusive data to support its routine use is lacking. Other strategies such as biologic therapies as with retinoids for SPTCL have provided durable benefit for some patients with less toxicity. Ultimately, it will take larger series with these rare but increasingly recognized entities to better define a preferred management approach.

Splenic tumor presenting as pyrexia of unknown origin.

Pyrexia of unknown origin has always been a challenging problem to diagnose for physicians. Here we present a case of a splenic tumor, which after histopathology and immunohistochemistry, two possibilities were considered, a diffuse large cell lymphoma--plasmablastic variant and second an anaplastic plasmacytoma. The patient was treated with chemotherapy and on followup he has no evidence of recurrence or any residual lesion.