Unusual Mesenchymal Tumors of the Lower Gastrointestinal Tract: When You Hear Hoofbeats in the Night, Do Not Forget the Zebras.

INTRODUCTION: Little information about clinical presentation of mesenchymal tumors of the lower gastrointestinal (GI) tract due to their extreme heterogeneity is available for clinical management. Usually, small solitary asymptomatic polyps are accidently found during a screening colonoscopy performed for hematochezia, abdominal pain, constipation, diarrhea, and bowel obstruction. In this case series, we illustrate our experience with mesenchymal tumors of the lower GI tract, which are a group of unusual and quite challenging lesions. CASE PRESENTATION: We retrospectively collected mesenchymal tumors of the lower GI tract in our institution (Fondazione IRCSS Ca' Granda - Ospedale Maggiore Policlinico di Milano) during the last 10 years. We reviewed the histological slides, and, when necessary, we performed immunohistochemical analyses to better characterize the tumors. A total of 99 cases were identified: 45 GISTs, 42 lipomas, 4 leiomyomas, 3 Kaposi sarcomas, 1 schwannoma, 1 ganglioneuroma, 1 hemangioma, 1 inflammatory fibroid polyp, and 1 challenging case of spindle cell melanoma. We focused on the most rare entities excluding therefore all GISTs and lipomas from re-evaluation. CONCLUSION: Mesenchymal tumors of the lower GI tract represent a highly heterogeneous group of lesions encompassing GISTs, lipomas, smooth muscle tumors (leiomyoma and leiomyosarcoma), GI schwannomas, inflammatory fibroid polyps, solitary fibrous tumors, and other unusual spindle cell tumors. Immunohistochemistry and, in selected cases, molecular biology remain a useful tool which, in addition to a meticulous study of the morphology, helps the pathologist in the tangled jungle of differential diagnosis.

CD34-Positive Blast Count and p53 Expression in Bone Marrow Biopsies of Patients with Low-Risk Myelodysplastic Syndromes: Potential Predictive Tools of Response to Erythropoietin Stimulating Agents.

INTRODUCTION: The first-line therapy for patients with low-risk myelodysplastic syndromes (MDSs) commonly consists of erythropoietin stimulating agents (ESAs), with a response rate ranging from 34 to 62%. For nonresponder patients, outside clinical trials, blood transfusions are the most frequent therapeutic option, with detrimental effect on the quality of life and with risks of iron-overload. Since no studies have been yet conducted on this topic, we investigated the potential predictive role of bone marrow (BM) histological evaluation in patients treated with ESAs. MATERIALS AND METHODS: We performed a morphological and immunohistochemical retrospective analysis of BM biopsies of 96 patients with low-risk MDSs subsequently treated with ESAs. RESULTS: In our series, substantial morphological overlap was found between responder and nonresponder patients. On the contrary, patients with a percentage of CD34-positive blasts >3% or with p53 protein expression <1% responded with a significantly higher frequency to ESAs. CONCLUSIONS: Our study reinforces the role of BM biopsy as diagnostic tool in MDSs, being also able to supply information related to response to ESAs and to its loss over time.

Recent advances and current controversies in lung neuroendocrine neoplasms✰.

In the lung, neuroendocrine tumors (NETs), namely typical and atypical carcinoids, and neuroendocrine carcinomas (NECs), grouping small cell carcinoma (SCLC) and large cell neuroendocrine carcinoma (LCNEC), make up for distinct tumor entities according to epidemiological, genetic, pathologic and clinical data. The proper classification is essential in clinical practice for diagnosis, prognosis and therapy purposes. Through an extensive literature survey, three perspectives on lung NENs have been revised: i) criteria and terminology on biopsy or cytology samples of primaries or metastases; ii) carcinoids with elevated mitotic counts and/or Ki-67 proliferation rates; iii) relevance of molecular landscape to identify new tumor entities and therapeutic targets. Furthermore, a dispute about lung NEN development has been raised according to emerging molecular models. We herein provide a pathology update on practical topics in the setting of lung NENs according to the current classification (recent advances). We have also reappraised the development of these tumors by modeling risk factors and natural history of disease (recent controversies). Combining recent advances and controversies may help clarify our biological understanding of lung NENs and give practical information for the clinical decision-making process.

Lymphocytic Infiltrate and p53 Protein Expression as Predictive Markers of Response and Outcome in Myelodysplastic Syndromes Treated with Azacitidine.

High-risk Myelodysplastic syndromes (MDS) represent therapeutical challenges and are usually managed with hypomethylating agents such as azacitidine. Given the lack of data in the literature concerning azacitidine effects on bone marrow, we retrospectively analyzed 57 high-risk MDS cases in order to identify any changes induced by azacitidine therapy or relevant correlations between therapy response and pre- or post-treatment features. Azacitidine treatment had no significant impact on bone marrow cellularity or morphological dysplastic features. On the contrary, although not statistically significant, we observed a slight decrease in CD34+ and CD117+ blasts and p53+ precursors after treatment. Moreover, pre-treatment IPSS-R cytogenetic score (p = 0.004), lymphocytic infiltrate (p = 0.017) and p53+ elements (p = 0.001) correlated with AML progression; pre-treatment lymphocytic infiltrate was also linked to better response to therapy (p = 0.004), suggesting an anti-tumoral role of bone marrow microenvironment. Post-treatment blast count impacted negatively on overall survival (p = 0.035) and risk of leukemic progression (p = 0.04), while both post-treatment lymphocytic infiltrate and p53+ elements showed significant correlation with treatment response (p = 0.004 and p = 0.003 respectively). Higher post-treatment p53+ elements correlated also with risk of leukemic progression (p = 0.013). Our results suggest the possible role of lymphocytic infiltrate and p53+ elements as predictive markers in MDS treated with azacitidine, disclosing new chapters in the understanding of MDS evolution and treatment.

A Subset of Large Cell Neuroendocrine Carcinomas in the Gastroenteropancreatic Tract May Evolve from Pre-existing Well-Differentiated Neuroendocrine Tumors.

In the gastro-entero-pancreatic (GEP) tract, neuroendocrine neoplasms (NENs) include well differentiated neuroendocrine tumors (NETs) and high-grade NE carcinomas (NECs), which are thought to make up separate and mutually exclusive tumor entities. Little is known, however, as to whether there may be any pathogenetic link between them. Clustering analysis of a 10-gene panel generated from a previously reported next-generation sequencing analysis on 48 GEP-NENs with clinical annotations was used in the study. Unsupervised cluster analysis showed three histology-independent clusters, namely, C1, C2, and C3, which accounted for 44% of patients but the entire array of mutations. All but two NECs fell into the clusters, yet with different prevalence rates (p < 0.0001). A model was devised according to which NETs were likely to evolve into NECs upon progression of C3 into C1 and C2, despite different morphology. The median Ki-67 labeling index was 5% in C3 showing better prognosis and 50% in C1 and C2 experiencing worse prognosis, with an impressive intra-tumor heterogeneity of diversely proliferating tumor areas. This study suggests that a subset of large cell NECs in the gastroenteropancreatic tract may evolve from pre-existing well-differentiated NETs.

Cutaneous tricholemmal carcinoma: a 15-year single center experience.

BACKGROUND: Clear cell morphology has been described in several cutaneous neoplasms either as a specific feature of some entities either as a morphological variant in the spectrum, and these two entities are frequently considered together in the differential diagnosis. METHODS: We reviewed our series of cases occurred in our laboratory in order to further quantify the number of cases showing morphological features of tricholemmal differentiation and to investigate other clinical or histological difference. We retrieved 91 cases and, for each of them, all the clinical data regarding age, sex, clinical features, and clinical suspicious were collected, when available. RESULTS: The revision of the specimens concluded with a final diagnosis of tricholemmal carcinoma in 15 cases (17%), all the other cases were thus considered as squamous cell carcinoma with clear cell features. No statistically significant correlations were observed with the demografic or clinicopatholagical parameters such as age, sex or dimensions, but morphological revision highlighted a potentially greater "vertical" growth frequently not matched by a concomitant radial one in tricholemmal carcinoma than in squamous tumors. CONCLUSIONS: The debate upon the diagnostic distinction of these tumors is still ongoing with authors proposing the tricholemmal carcinoma as a variant of a squamous cell carcinoma rather than a distinct entity. Further studies are needed to confirm our data and to evaluate the reproducibility of this feature.

Clinical implications of lung neuroendocrine neoplasm classification.

INTRODUCTION: Neuroendocrine neoplasms of the lung (Lung NENs) encompass NE tumors (NETs), which are in turn split into typical and atypical carcinoids, and NE carcinomas (NECs), which group together small-cell carcinoma and large-cell NE carcinoma. This classification is the current basis for orienting the daily practice of these patients, with diagnostic, prognostic, and predictive inferences. AREAS COVERED: The clinical implications of lung NEN classification are addressed according to three converging perspectives, which were dissected through an extensive literature overview: (1) how to put intratumor heterogeneity into the context of the current classification; (2) how to contextualize immunohistochemistry markers to improve diagnosis, prognosis, and therapy prediction; and (3) how to use immuno-oncology strategies for life-threatening NECs, which still account for 90% or more of lung NENs. EXPERT OPINION: We provide practical insights to account for intratumor heterogeneity, practice the choice of immunohistochemistry markers, and emphasize once again the added value of immuno-oncology in the setting of personalized medicine of lung NENs.

Morphologic and molecular classification of lung neuroendocrine neoplasms.

Neuroendocrine neoplasms (NENs) of the lung encompass neuroendocrine tumors (NETs) composed of typical (TC) and atypical (AC) carcinoids and full-fledged carcinomas (NECs) inclusive of large cell neuroendocrine carcinoma (LCNEC) and small cell carcinoma (SCLC). NETs and NECs are thought to represent distinct and separate lesions with neither molecular overlap nor common developmental continuum. Two perspectives were addressed regarding the morphologic and molecular classification of lung NENs: (i) a supervised approach by browsing the traditional classification, the relevant gene alterations, and their clinical implications; and (ii) an unsupervised approach, by reappraising neoplasms according to risk factors and natural history of disease to construct an interpretation model relied on biological data. We herein emphasize lights and shadows of the current classification of lung NENs and provide an alternative outlook on these tumors focused on what we currently know about the biological determinants and the natural history of disease.

CXCL12 expression is a bona fide predictor of recurrence in lung neuroendocrine tumours; a multicentric study with emphasis on atypical carcinoids - a short report.

PURPOSE: Neuroendocrine tumors of the lung (LNETs) encompass a heterogeneous group of lesions, including tumors with no or low metastatic potential, such as typical (TCs) and atypical (ACs) carcinoids, and highly aggressive neuroendocrine carcinomas. To date, only a few biomarkers with prognostic impact have been identified in LNETs. Previous experimental studies have suggested that the cytokine CXCL12 might have a role in stratifying the outcome of lung cancer as well as LNET patients. However, the reliability of immunohistochemical (IHC) tissue expression of CXCL12 in evaluating the prognosis of resected LNETs is currently not known. METHODS: Here, we subjected a cohort of 112 resected LNETs specifically enriched for ACs to IHC for CXCL12 and Ki67 using routine procedures. The clinical value of CXCL12 was assessed by applying the Cox proportional-hazards model to overall and disease-free survival rates. RESULTS: We found that CXCL12 was expressed in 8.3 to 38% of LNETs, depending on the different diagnostic categories. Upon survival analysis, when considering the whole cohort, we found that CXCL12-positive cases exhibited shorter disease-free survival rates compared to CXCL12-negative cases. Among ACs, tumors overexpressing CXCL12 showed significantly shorter disease-free survival rates. Finally, we found that the Ki67 index in ACs was higher in the CXCL12-positive cases. CONCLUSION: CXCL12 immunohistochemistry may serve as a potentially useful tool to better stratify LNETs, and more specifically ACs, in clinical practice.