Role of Myeloid-Derived Suppressor Cells in tumor-associated pregnancy

Cancer progression is dependent, in part, on interactions between tumor cells and the host microenvironment. During pregnancy, physiological changes occur that include inflammation and reduced immunity, both of which can promote tumor growth. Accordingly, tumors are observed to be more aggressive and to have greater proclivity toward metastasis during pregnancy. In this work, myeloid-derived suppressor cells (MDSC), a population of heterogeneous and pluripotent cells that can down-regulate immune responses during pathological conditions, were studied in the context of mouse and human gestation. The gene expression profile of mouse MDSC has been shown to differ in pregnant and virgin mice, and the profile in pregnant animals bears similarity to that of MDSC associated with the tumor microenvironment. Common induced genes include Fibronectin1 and Olfactomedin4, which are known to be involved in extracellular matrix remodeling and tissue permissiveness to tumor cells implantation. Our observations suggest that mouse MDSC may represent a shared regulatory mechanism of tissue permissiveness that occurs during the physiological state of gestation and tumor growth. Pregnancy-associated changes in immunosuppressive myeloid cell activity have also been studied in humans. We show that CD33+ myeloid cells isolated from PBMC (peripheral blood mononuclear cells) of pregnant women are more strongly immunosuppressive on T cells than CD33+ cells removed from non-pregnant subjects. During murine gestation, decreased natural killer (NK) cell activity is responsible, at least in part, for the increase in experimental metastasis. However, although peripheral blood NK cell numbers and cytotoxicity were slightly reduced in pregnant women, neither appeared to be regulated by CD33+ cells. Nevertheless, based on its observed suppression of T cell responses, the CD33+ PBMC subset appears to be an appropriate myeloid cell population to study in order to elucidate mechanisms of immune regulation that occur during human pregnancy. Our findings regarding the immunosuppressive function of CD33+cells and the role of NK cells during human pregnancy are consistent with the notion that changes in the function of the immune system participate in the constitution of a permissive soil for tumour progression.

Distinct phenotypes of antigen-selected CD8 T cells emerge at different stages of an in vivo immune response.

We have previously described a unique system for identifying Ag-selected CD8 T cells during an in vivo response in normal mice. In this system, lymphocytes isolated from DBA/2 mice injected i.p. with HLA-CW3 transfected syngeneic (H-2d) P815 cells show a remarkable expansion of CD8 cells that utilize TCR expressing the V beta 10 gene segment and additional structural features characteristic of Kd-restricted CW3-specific CTL clones. We have now taken advantage of this system to characterize the surface phenotype of CD8 cells selected by Ag in vivo. We observed several distinct phenotypes at different stages of the response. At the peak of the response, Ag-selected cells were low in CD62L and CD45RB expression but displayed high levels of CD44. In addition, there was a partial down-regulation of CD8 and TCR. Cells of this phenotype were present in lymphoid tissues for several mo after immunization. Much later in the response, Ag-selected cells expressed higher levels of CD8 and TCR. Moreover, a distinct subset of these long-term immune cells emerged that now expressed CD62L and CD45RB. Analysis of CD8 cells from different tissues also revealed certain differences, particularly in TCR and co-receptor levels from liver-derived cells compared with circulating cells at the peak of the response. Our findings suggest that the function of Ag-selected CD8 cells may be regulated over time and according to location by subtle changes in cell-surface phenotype.

IRF6 is a mediator of Notch pro-differentiation and tumour suppressive function in keratinocytes.

While the pro-differentiation and tumour suppressive functions of Notch signalling in keratinocytes are well established, the underlying mechanisms remain poorly understood. We report here that interferon regulatory factor 6 (IRF6), an IRF family member with an essential role in epidermal development, is induced in differentiation through a Notch-dependent mechanism and is a primary Notch target in keratinocytes and keratinocyte-derived SCC cells. Increased IRF6 expression contributes to the impact of Notch activation on growth/differentiation-related genes, while it is not required for induction of 'canonical' Notch targets like p21(WAF1/Cip1), Hes1 and Hey1. Down-modulation of IRF6 counteracts differentiation of primary human keratinocytes in vitro and in vivo, promoting ras-induced tumour formation. The clinical relevance of these findings is illustrated by the strikingly opposite pattern of expression of Notch1 and IRF6 versus epidermal growth factor receptor in a cohort of clinical SCCs, as a function of their grade of differentiation. Thus, IRF6 is a primary Notch target in keratinocytes, which contributes to the role of this pathway in differentiation and tumour suppression.

Neutrophils activate plasmacytoid dendritic cells by releasing self-DNA-peptide complexes in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a severe and incurable autoimmune disease characterized by chronic activation of plasmacytoid dendritic cells (pDCs) and production of autoantibodies against nuclear self-antigens by hyperreactive B cells. Neutrophils are also implicated in disease pathogenesis; however, the mechanisms involved are unknown. Here, we identified in the sera of SLE patients immunogenic complexes composed of neutrophil-derived antimicrobial peptides and self-DNA. These complexes were produced by activated neutrophils in the form of web-like structures known as neutrophil extracellular traps (NETs) and efficiently triggered innate pDC activation via Toll-like receptor 9 (TLR9). SLE patients were found to develop autoantibodies to both the self-DNA and antimicrobial peptides in NETs, indicating that these complexes could also serve as autoantigens to trigger B cell activation. Circulating neutrophils from SLE patients released more NETs than those from healthy donors; this was further stimulated by the antimicrobial autoantibodies, suggesting a mechanism for the chronic release of immunogenic complexes in SLE. Our data establish a link between neutrophils, pDC activation, and autoimmunity in SLE, providing new potential targets for the treatment of this devastating disease.

An anti-CD19 antibody coupled to a tetanus toxin peptide induces efficient Fas ligand (FasL)-mediated cytotoxicity of a transformed human B cell line by specific CD4+ T cells.

Treatment of B cell lymphoma patients with MoAbs specific for the common B cell marker (CD20) has shown a good overall response rate, but the number of complete remissions is still very low. The use of MoAbs coupled to radioisotopes can improve the results, but induces undesirable myelodepression. As an alternative, we proposed to combine the specificity of MoAbs with the immunogenicity of T cell epitopes. We have previously shown that an anti-Ig lambda MoAb coupled to an MHC class II-restricted universal T cell epitope peptide P2 derived from tetanus toxin induces efficient lysis of a human B cell lymphoma by a specific CD4+ T cell line. Here we demonstrate that the antigen presentation properties of the MoAb peptide conjugate are maintained using a MoAb directed against a common B cell marker, CD19, which is known to be co-internalized with the B cell immunoglobulin receptor. In addition, we provide evidence that B cell lysis is mediated by the Fas apoptosis pathway, since Fas (CD95), but not tumour necrosis factor receptor (TNFr) or TNF-related receptors, is expressed by the target B cells, and FasL, but not perforin, is expressed by the effector T cells. These results show that B cell lymphomas can be 'foreignized' by MoAb-peptide P2 conjugates directed against the common B cell marker CD19 and eliminated by peptide P2-specific CD4+ T cells, via the ubiquitous Fas receptor. This approach, which bridges the specificity of passive antibody therapy with an active T cell immune response, may be complementary to and more efficient than the present therapy results with unconjugated chimeric anti-CD20 MoAbs.

Dexamethasone induces posttranslational degradation of GLUT2 and inhibition of insulin secretion in isolated pancreatic beta cells. Comparison with the effects of fatty acids.

GLUT2 expression is strongly decreased in glucose-unresponsive pancreatic beta cells of diabetic rodents. This decreased expression is due to circulating factors distinct from insulin or glucose. Here we evaluated the effect of palmitic acid and the synthetic glucocorticoid dexamethasone on GLUT2 expression by in vitro cultured rat pancreatic islets. Palmitic acid induced a 40% decrease in GLUT2 mRNA levels with, however, no consistent effect on protein expression. Dexamethasone, in contrast, had no effect on GLUT2 mRNA, but decreased GLUT2 protein by about 65%. The effect of dexamethasone was more pronounced at high glucose concentrations and was inhibited by the glucocorticoid antagonist RU-486. Biosynthetic labeling experiments revealed that GLUT2 translation rate was only minimally affected by dexamethasone, but that its half-life was decreased by 50%, indicating that glucocorticoids activated a posttranslational degradation mechanism. This degradation mechanism was not affecting all membrane proteins, since the alpha subunit of the Na+/K+-ATPase was unaffected. Glucose-induced insulin secretion was strongly decreased by treatment with palmitic acid and/or dexamethasone. The insulin content was decreased ( approximately 55 percent) in the presence of palmitic acid, but increased ( approximately 180%) in the presence of dexamethasone. We conclude that a combination of elevated fatty acids and glucocorticoids can induce two common features observed in diabetic beta cells, decreased GLUT2 expression, and loss of glucose-induced insulin secretion.

The chemokine receptor CXCR4 strongly promotes neuroblastoma primary tumour and metastatic growth, but not invasion.

Neuroblastoma (NB) is a heterogeneous, and particularly malignant childhood neoplasm in its higher stages, with a propensity to form metastasis in selected organs, in particular liver and bone marrow, and for which there is still no efficient treatment available beyond surgery. Recent evidence indicates that the CXCR4/CXCL12 chemokine/receptor axis may be involved in promoting NB invasion and metastasis. In this study, we explored the potential role of CXCR4 in the malignant behaviour of NB, using a combination of in vitro functional analyses and in vivo growth and metastasis assessment in an orthotopic NB mouse model. We show here that CXCR4 overexpression in non-metastatic CXCR4-negative NB cells IGR-NB8 and in moderately metastatic, CXCR4 expressing NB cells IGR-N91, strongly increased tumour growth of primary tumours and liver metastases, without altering the frequency or the pattern of metastasis. Moreover shRNA-mediated knock-down experiments confirmed our observations by showing that silencing CXCR4 in NB cells impairs in vitro and almost abrogates in vivo growth. High levels of CXCL12 were detected in the mouse adrenal gland (the primary tumour site), and in the liver suggesting a paracrine effect of host-derived CXCL12 on NB growth. In conclusion, this study reveals a yet unreported NB-specific predominant growth and survival-promoting role of CXCR4, which warrants a critical reconsideration of the role of CXCR4 in the malignant behaviour of NB and other cancers.

Monitoring of NY-ESO-1 specific CD4+ T cells using molecularly defined MHC class II/His-tag-peptide tetramers.

MHC-peptide tetramers have become essential tools for T-cell analysis, but few MHC class II tetramers incorporating peptides from human tumor and self-antigens have been developed. Among limiting factors are the high polymorphism of class II molecules and the low binding capacity of the peptides. Here, we report the generation of molecularly defined tetramers using His-tagged peptides and isolation of folded MHC/peptide monomers by affinity purification. Using this strategy we generated tetramers of DR52b (DRB3*0202), an allele expressed by approximately half of Caucasians, incorporating an epitope from the tumor antigen NY-ESO-1. Molecularly defined tetramers avidly and stably bound to specific CD4(+) T cells with negligible background on nonspecific cells. Using molecularly defined DR52b/NY-ESO-1 tetramers, we could demonstrate that in DR52b(+) cancer patients immunized with a recombinant NY-ESO-1 vaccine, vaccine-induced tetramer-positive cells represent ex vivo in average 1:5,000 circulating CD4(+) T cells, include central and transitional memory polyfunctional populations, and do not include CD4(+)CD25(+)CD127(-) regulatory T cells. This approach may significantly accelerate the development of reliable MHC class II tetramers to monitor immune responses to tumor and self-antigens.

Immune response to mouse mammary tumour virus.

Superantigens of mouse mammary tumor virus induce a strong cognate interaction between T cells and B cells. In addition to amplifying the virus-infected B-cell pool, this superantigen-driven interaction leads to the differentiation of virus-specific B cells into plasma cells. Successful interaction between T cells and B cells is required for completion of the viral life cycle.

Characterization of CD4+ CD25+ T cells in solid organ transplant recipients

Although important progresses have been achieved in the therapeutic management of transplant recipients, acute and chronic rejections remain the leading causes of premature graft loss after solid organ transplantation. This, together with the undesirable side effects of immunosuppressive drugs, has significant implications for the long-term outcome of transplant recipients. Thus, a better understanding of the immunological events occurring after transplantation is essential. The immune system plays an ambivalent role in the outcome of a graft. On one hand, some T lymphocytes with effector functions (called alloreactive) can mediate a cascade of events eventually resulting in the rejection, either acute or chronic, of the grafted organ ; on the other hand, a small subset of T lymphocytes, called regulatory T cells, has been shown to be implicated in the control of these harmful rejection responses, among other things. Thus, we focused our interest on the study of the balance between circulating effectors (alloreactive) and regulatory T lymphocytes, which seems to play an important role in the outcome of allografts, in the context of kidney transplantation. The results were correlated with various variables such as the clinical status of the patients, the immunosuppressive drugs used as induction or maintenance agents, and past or current episodes of rejection. We observed that the percentage of the alloreactive T lymphocyte population was correlated with the clinical status of the kidney transplant recipients. Indeed, the highest percentage was found in patients suffering from chronic humoral rejection, whilst patients on no or only minimal immunosuppressive treatment or on sirolimus-based immunosuppression displayed a percentage comparable to healthy non-transplanted individuals. During the first year after renal transplantation, the balance between effectors and regulatory T lymphocytes was tipped towards the detrimental effector immune response, with the two induction agents studied (thymoglobulin and basiliximab). Overall, these results indicate that monitoring these immunological parameters may be very useful for the clinical follow-up of transplant recipients ; these tests may contribute to identify patients who are more likely to develop rejection or, on the contrary, who tolerate well their graft, in order to adapt the immunosuppressive treatment on an individual basis.

18F-FLT and 125I-IdUrd uptake increase in human tumour cell lines induced by the thymidylate synthase inhibitor FdUrd.

Aim: 5-fluoro-2'-deoxyuridine (FdUrd) depletes the endogenous 5'-deoxythymidine triphosphate (dTTP) pool. We hypothesized whether uptake of exogenous dThd analogues could be favoured through a feedback enhanced salvage pathway and studied the FdUrd effect on cellular uptake of 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) and 5-125I-iodo-2'-deoxyuridine (125I-IdUrd) in different cancer cell lines in parallel. Methods: Cell uptake of 18F-FLT and 125I-IdUrd was studied in 2 human breast, 2 colon cancer and 2 glioblastoma lines. Cells were incubated with/without 1 µmol/l FdUrd for 1 h and, after washing, with 1.2 MBq 18F-FLT or 125I-IdUrd for 0.3 to 2 h. Cell bound 18F-FLT and 125I-IdUrd was counted and expressed in % incubated activity (%IA). Kinetics of 18F-FLT cell uptake and release were studied with/without FdUrd modulation. 2'-3H-methyl-fluorothymidine (2'-3H-FLT) uptake with/without FdUrd pretreatment was tested on U87 spheroids and monolayer cells. Results: Basal uptake at 2 h of 18F-FLT and 125I-IdUrd was in the range of 0.8-1.0 and 0.4-0.6 Bq/cell, respectively. FdUrd pretreatment enhanced 18F-FLT and 125I-IdUrd uptake 1.2-2.1 and 1.7-4.4 fold, respectively, while co-incubation with excess thymidine abrogated all 18F-FLT uptake. FdUrd enhanced 18F-FLT cellular inflow in 2 breast cancer lines by factors of 1.8 and 1.6, respectively, while outflow persisted at a slightly lower rate. 2'-3H-FLT basal uptake was very low while uptake increase after FdUrd was similar in U87 monolayer cells and spheroids. Conclusions: Basal uptake of 18F-FLT was frequently higher than that of 125I-IdUrd but FdUrd induced uptake enhancement was stronger for 125I-IdUrd in five of six cell lines. 18F-FLT outflow from cells might be an explanation for the observed difference with 125I-IdUrd.

IRF6 is a mediator of the Notch pro-differentiation and tumour suppressive function in keratinocytes

I. Résumé large publicIRF6 est un médiateur de Notch dans la différenciation des kératinocytes et dans sa fonction de suppresseur de tumeursLa peau est l'organe le plus important du corps humain, elle représente chez l'adulte une surface d'environ 1,5 m2 et elle est composée de 2000 milliards de cellules. La peau est composée de plusieurs types cellulaires dont les kératinocvtes. Ces cellules, qui se trouvent dans la couche la plus externe de la peau (Pépiderme), nous protègent de la déshydratation et des agressions externes telles que les infections et rayons ultraviolets. Cette fonction de « barrière » est mise en place grâce à un processus appelé différenciation des kératinocvtes durant lequel les kératinocytes deviennent matures et finalement meurent pour former la couche cornée la plus externe difficilement pénétrable. L'homéostasie tissulaire est un mécanisme qui régule l'équilibre entre prolifération, différentiation et mort cellulaire. Une perturbation de cet équilibre peut mener à la formation d'une tumeur. Il existe différents types de tumeurs de la peau. Nous nous sommes intéressés aux «carcinomes spino-cellulaires» (SCC) qui se développent à partir des keratinocytes en différenciation. Notch est une molécule impliquée positivement dans la différenciation des kératinocytes et joue un rôle prépondérant dans la suppression des tumeurs kératinocytaires comme les SCC dans lesquelles Notch est faiblement exprimé. L'implication de Notch dans la différenciation et dans la carcinogenèse kératinocytaire n'est plus controversée, mais les mécanismes qui sont à la base de ces fonctions restent encore à élucider. IRfF6 est une protéine qui, d'après sa structure, a été classée parmi une famille de régulateurs de la défense de l'organisme (IRFs). Des études ultérieures ont montré qu'IRf 6 n'a pas de rôle dans la réponse immunitaire mais qu'il est plutôt impliqué dans le développement de l'épiderme. Dans ce travail, nous avons établi que, dans les kératinocytes, l'expression d'IPJF6 est contrôlé par Notch et que, comme pour ce dernier, elle est réduite dans les SCCs. De plus, nous avons observé qu'IRF6 régule les mêmes gènes que Notch, et qu'il est en effet un médiateur de la fonction de Notch dans la différenciation des kératinocytes. Parmi les gènes contrôlés par l'axe Notch-IRF6 il y en a trois qui sont sur-exprimés dans les SCCs et qui sont réprimés par cet axe. Il s'agit d'une part d'IRF3 et IRF7, deux autres membres de la famille IRF, et du récepteur EGFR (Epidermal growth factor receptor), un oncogène (un gène impliqué dans l'accélération de la formation de tumeurs). Dans leur ensemble, ces découvertes nous informent sur les mécanismes impliqués dans les fonctions pro-differentiatrice et tumeur suppressive de Notch. Plus encore, elles ouvrent des perspectives intéressantes quant au développement de nouvelles approches thérapeutiques dans le traitement des cancers.II. RésuméLa voie de signalisation de Notch joue un rôle très important dans la différenciation cellulaire et dans la carcinogenèse de nombreux tissus. Dans les kératinocytes, elle agit comme suppresseur de tumeurs, fonction altérée dans les cancers spino cellulaires SCC (tumeurs kératinocytaires) de part la perte d'expression de Notch.Bien que les fonctions pro-différenciatrice et tumeur-suppressive de la voie de signalisation de Notch soient aujourd'hui reconnues, les mécanismes sous-jacents restent à explorer.Dans ce travail, nous montrons qu'IRF6, un membre de la famille des régulateurs de la voie de l'interféron (IRF), ne possédant pas de rôles dans la réponse immunitaire mais essentiel dans le développement de l'épiderme, est d'autant plus exprimé que le kératinocytes sont différenciées alors que son expression est drastiquement diminuée dans les SCC. De façon intéressante, l'expression d'IRF6 durant la différenciation kératinocytaire est directement contrôlée par Notch.Dans les kératinocytes l'expression accrue d'IRP6 a les mêmes effets que 1'activation de la voie de Notch induisant les marqueurs de différentiation des couches supra-basales de l'épiderme et inhibant ceux de la couche basale impliqués dans la prolifération cellulaire. Cependant IRF6 n'est pas impliqué dans la régulation d'autres cibles de Notch, comme p21WAFI/CiP' et Hesl. Comme Notch, IRF6 contrôle négativement l'expression de EGFR et IRF3/7. De ce fait EGFR et IRF3 et IRF7 sont fortement exprimés dans les SCCs humaines où l'expression de Notch et IRF6 est fortement réduite.En conclusion, nous avons démontré qu'IRF6 est une cible directe de Notch/CSL dans les keratinocytes qui medie les effets "non-canonique" de cette voie de signalisation dans la différentiation et dans la suppression tumorale.III. SummaryThe Notch pathway is an important regulator of differentiation and carcinogenesis. In keratinocytes it acts as tumour suppressor and the Notch gene is markedly reduced in keratinocyte-derived squamous cell carcinoma (SCC). While the pro-differentiation and tumour suppressive functions of Notch signalling in keratinocytes are well established, the underlying mechanisms are still poorly understood, We report here that Interferon Regulatory Factor 6 (IRF6), an IRF family member with an essential role in epidermal development, is downmodulated in SCC and is induced in differentiating cells. We observed that the induction of IRF6 in differentiating keratinocytes is suppressed by Notch inhibition. IRF6 expression is also decreased in mice with keratinocyte-specific deletion of the Notch 1/2.Moreover we show that the expression of this gene is induced by Notch activation through a CSL-dependent mechanism even under conditions of protein synthesis inhibition, with endogenous Notch 1 binding to the IRF6 promoter.Increased IRJF6 expression is necessary for the impact of Notch activation on differentiation markers K1 and Involucrin, and proliferation markers integrins and p63, but not on other "canonical" Notch targets like p21WAF1/Cipl, Hes1 and Hey1. Like Notch 1, IRF6 down-modulates expression of epidermal growth factor receptor (EGFR) as well as two other IRF family members, IRF3 and 7, which we previously linked to positive control of p63 expression. Expression of IRF3, IRF7 and EGFR is enhanced in cutaneous squamous cell carcinomas, illustrating a strikingly opposite pattern compared to Notch and IRF6.Thus, IRF6 is a primary Notch target in keratinocytes, which mediates the effects of this pathway on differentiation and contributes to tumor suppression.

Lipid metabolism in myelinating glial cells: lessons from human inherited disorders and mouse models.

The integrity of central and peripheral nervous system myelin is affected in numerous lipid metabolism disorders. This vulnerability was so far mostly attributed to the extraordinarily high level of lipid synthesis that is required for the formation of myelin, and to the relative autonomy in lipid synthesis of myelinating glial cells because of blood barriers shielding the nervous system from circulating lipids. Recent insights from analysis of inherited lipid disorders, especially those with prevailing lipid depletion and from mouse models with glia-specific disruption of lipid metabolism, shed new light on this issue. The particular lipid composition of myelin, the transport of lipid-associated myelin proteins, and the necessity for timely assembly of the myelin sheath all contribute to the observed vulnerability of myelin to perturbed lipid metabolism. Furthermore, the uptake of external lipids may also play a role in the formation of myelin membranes. In addition to an improved understanding of basic myelin biology, these data provide a foundation for future therapeutic interventions aiming at preserving glial cell integrity in metabolic disorders.

Melanotic neuroectodermal tumour of infancy: a case report and review of the aetiopathogenic hypotheses.

The case of a 2-month-old healthy infant without relevant medical history. The patient was referred due to the aggravation of a swelling occupying the left half of the anterior maxilla. This lesion became visible approximately one month ago; it involved the buccal gingiva and alveolar bone, including the deciduous tooth germs 6.1 and 6.2. The swelling had dimensions of 20 mm x 20 mm. The surgical excision was performed under general anesthesia. The tooth buds of 6.1 and 6.2 were closely related to the tumour and so were removed. The lesion was entirely enucleated. The pathology of the lesion confirmed a melanotic neuroectodermal tumour of infancy. The melanotic neuroectodermal tumour of infancy (MNTI) has been described as a rare benign pigmented painless swelling that usually occurs in the anterior region of the maxilla and in the incisor region. The histological examination showed small basophilic cells, many containing melanin pigmentation within the cytoplasm, with a second population of larger cubical cells with abundant cytoplasm, arranged in alveolar or adenoid clusters. According to Krompecher this tumour derives from epithelial nests evolved at the time of embryonic fusion of the facial processes. It has also been suggested that the tumour arises from the retinal anlage by a pinching-off process of neuroepithelium during the formation of embryonic eye. More recently, the presence of high levels of vanillylmandelic acid suggest a neural origin of the tumour.

An unusual uterine tumour with signet ring cell features

Objective: Lymphomas with signet ring cell features are rare, as is uterine dissemination of lymphomas. We report an exceptional case of a uterine tumor combining these two characteristics. Method: A 61-year-old female was diagnosed in 2004 with localized nodal grade 2 follicular lymphoma (stage IA). She received local radiation therapy, experienced total remission, and did well until 2009 when a systematic CT scan evidenced a pelvic anterior-lateral mass. Total enlarged hysterectomy was performed. Results: The anterior uterine wall contained a 4.8-cm fish flesh well-delineated mass corresponding to a mostly diffuse and focally nodular proliferation of medium to large cells with extensive signet ring cell changes. Tumor cells were CD20-, CD10-, Bcl2-, and Bcl6-positive with a low proliferation rate (<10-15%); CD21 underlined a focal follicular architecture. The vacuoles were PAS-negative and did not stain for immunoglobulin; ultrastructural analysis revealed nonspecific degenerative vacuoles. No lymph nodes were identified isolated from the surgical specimen. The tumor was considered as a secondary localization of the systemic follicular lymphoma, though no signet ring cells were evidenced in the cervical lymph node biopsy (reviewed). Follow-up showed retroperitoneal tissue infiltration (PET-CT) and normal medullar biopsy. She recently started R-CHOP chemotherapy. Conclusion: This case illustrates both an unusual site of dissemination and challenging cytological characteristics in a follicular lymphoma. The signet ring cell changes challenged the adequate classification of this lymphoma as either a large B cell or a follicular B cell lymphoma.