Complicated appendiceal diverticulosis versus low-grade appendiceal mucinous neoplasms: a major diagnostic dilemma.

AIMS: To research and identify how often complicated diverticular disease of the appendix [appendiceal diverticular disease (ADD)] shows histological mimicry of low-grade appendiceal mucinous neoplasms (LAMNs) and to provide guidance on the useful histopathological features that allow the appropriate diagnosis to be made. METHODS AND RESULTS: Seventy-four cases of complicated appendiceal diverticular disease were identified from two specialist centres. Of the second opinion/consultation cases, 71% of the ADD cases had been diagnosed by referring pathologists as LAMNs. Salient pathological features were identified and agreed upon to reach the applicable diagnosis. For a diagnosis of complicated diverticulosis, particularly when associated with mucus cysts, the following morphological features were regarded as important: relative retention of the normal mucosal architecture with lamina propria and a maintained crypt architecture, crypts arranged in regular array, epithelial hyperplasia and a lack of nuclear abnormalities extending the length of the crypts. In a formal case-control study undertaken on 30 cases with each diagnosis, ADD and LAMN, loss of lamina propria, a filiform architecture and hypermucinosis were significantly associated with low-grade appendiceal mucinous neoplasms. Mucosal neuromas were significantly associated with diverticular disease of the appendix. CONCLUSIONS: To our knowledge, this study represents the largest series in the world literature and serves to highlight the important pathological features to distinguish complicated diverticular disease of the appendix from LAMNs, and emphasises the difficulties experienced by diagnostic pathologists in diagnosing complicated appendiceal diverticulosis. This is important, as LAMNs have a significant risk of transcoelomic spread, while complicated appendiceal diverticulosis has no such risk.

Analysis of Mutation and Loss of Heterozygosity by Whole-Exome Sequencing Yields Insights into Pseudomyxoma Peritonei.

Pseudomyxoma peritonei (PMP) is a clinical syndrome characterized by gross mucinous ascites originating from a disseminated intraperitoneal neoplasm. Although typically confined to the abdomen, mortality is high if untreated. Biomarkers, including genetic mutation profiles, may aid treatment selection and decision making. We applied whole-exome sequencing to five patients diagnosed with low-grade appendiceal mucinous neoplasms, using paired tumor and germline samples identify biomarkers. Multiple bioinformatic approaches were applied to these data to assess both somatic mutation profiles and loss of heterozygosity events. Mutation profiles of the tumors were consistent with deamination of methylcytosine being the prevailing mechanism. Pathogenic mutations were identified in both KRAS and GNAS in all samples, and further mutations in genes implicated in PMP, namely FGFR2, APC, SMAD2, and FAT4. No TP53 somatic mutations were identified, matching expectations for low-grade tumors. Four of five samples exhibited clonal loss of heterozygosity; these regions were further examined and found to contain genes harboring pathogenic somatic mutations in some samples. RNF43 was hereby implicated in the pathogenesis of PMP of appendiceal origin, having previously been found to increase sensitivity to Wnt signaling and to have involvement in similar mucinous tumors. In conclusion, we have investigated the mutation profile of PMP of appendiceal origin and provided the first report of RNF43 involvement in its progression.

Outcomes of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy for peritoneal mesothelioma and predictors of survival.

BACKGROUND: Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) benefits selected patients with peritoneal mesothelioma. We present the outcomes of this treatment strategy in a UK peritoneal malignancy national referral centre. METHODS: Observational retrospective analysis of data prospectively collected in a dedicated peritoneal malignancy database between March 1998 and January 2016. RESULTS: Of 1586 patients treated for peritoneal malignancy, 76 (4.8%) underwent surgery for peritoneal mesothelioma. Median age was 49 years (range 21-73 years). 34 patients (45%) were female. Of the 76 patients, 39 (51%) had low grade histological subtypes (mostly multicystic mesothelioma), and 37 (49%) had diffuse malignant peritoneal mesothelioma (DMPM; mostly epithelioid mesothelioma). Complete cytoreduction was achieved in 52 patients (68%) and maximal tumour debulking (MTD) was performed in 20 patients (26%); the remaining 4 patients (5%) underwent a laparotomy with biopsy only. HIPEC was administered in 67 patients (88%). Median overall (OS) and disease-free survival (DFS) after CRS was 97.8 (80.2-115.4) and 58.8 (47.4-70.3) months, respectively. After complete cytoreduction, 100% overall survival was observed amongst patients with low-grade disease. Ki-67 proliferation index was significantly associated with survival outcomes after complete cytoreduction for DMPM and was an independent predictor of decreased survival. CONCLUSION: With adequate patient selection (guided by histological classification and Ki-67 proliferation index) and complete cytoreduction with HIPEC, satisfactory outcomes can be achieved in selected patients with peritoneal mesothelioma.

A unique cause of a rare disorder, unilateral macromastia due to lymphangiomatosis of the breast: a case report.

Macromastia and in particular unilateral macromastia is a rare clinical entity. It relates to massive enlargement of the breast in non-obese women. This case report describes an initially mild unilateral asymmetry occurring nine months postpartum in a 33-year-old female. However, following her second pregnancy within 12 months, her left breast became severely enlarged. This did not improve on delivery. No discrete lesion was seen on imaging and no significant abnormalities were seen in her blood chemistry. Surgical treatment was a mammoplasty and 580 g of mammary tissue was removed. Grossly, there was spongiform subcutaneous tissue with diffuse extension. On histology, this consisted of a highly complex and diffuse pattern of infiltration and of cavernous empty channels lined by a delicate attenuated endothelium which was CD34 and D2-40 positive. The appearances were consistent with lymphangiomatosis, more commonly encountered in the limbs, heretofore. Lymphangiomatosis has not been previously described in breast tissue and only a single case report exists for such a lesion in axillary tissue. Treatment of such lesions in the periphery by surgical excision is very difficult and excision without being radical can be impossible. Follow up of our patient, shows no evidence of recurrence in this patient. Our case report describes the clinicopathological features, differential diagnosis to be considered and treatment, in addition to reviewing the relevant literature.

Embryonal rhabdomyosarcoma of the testis.

Rhabdomyosarcoma (RMS), arising from mesenchymal cells, is the most common soft tissue tumour in children and accounts for up to half of all sarcomas. We present the case of a 33-year-old male presented to the urology department of the University College Hospital Galway (Ireland) in March 2009 with a 2-month history of a left scrotal swelling, increasing in size.