ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Background & objectives: Micropapillary features in a colorectal carcinoma are associated with a poor prognosis because of the aggres- siveness of this variant. They present at a higher stage, with increased incidence of lymphovascular invasion and lymph node metastases. Methods: We present the case of a 64-year-old male known from 2020 with a sessile polyp located at the cecum-ascending junction, a recto-sigmoidal well differentiated adenocarcinoma (pT2N0) irra- diated followed by surgery and a frontal left sided meningioma. This year’s biopsy was reported as tubulo-villous adenoma with high-grade dysplasia and he presented in our clinic for the surgi- cal treatment. Results: On gross examination there was a 4 cm flat lesion, occupying three quarters of the colon’s circumference. On microscopy the tumour had features of a flat traditional serrated adenoma, with more than 50% showing ectopic crypt formation and typical cellular features with abun- dant eosinophilic cytoplasm and penicillate, centrally located nuclei. There were multiple foci of invasive carcinoma involving the upper submucosa, showing mostly micropapillary architecture - small clusters of cells delineated by stromal retraction. The cells showed marked pleo- morphism, abundant eosinophilic cytoplasm and prominent and multiple nucleoli. There was a marked neutrophil rich inflammation, including intra-tumoral micro-abscesses. We identified vascular and perineural invasion, without lymph node metastases. Conclusion: This case was signed out as flat TSA with multi- ple foci of micropapillary adenocarcinoma(pT1pN0). This is an interesting case because of the clinical course of the patient and the unusual morphology of this carcinoma. This carcinoma was this patient’s third tumour, that we know of, and the association with a meningioma and a serrated lesion is rare and could be syndromic. More tests need to be done in order to find the correlation between these entities if there is one. E-PS-06-034 Osseous metaplasia in colon cancer: a case report and lit- erature review A. Toma*, E. Tianu, O. Stefan, F. Obrocea *Colentina Clinical Hospital, Romania Background & objectives: Osseous metaplasia is defined as hetero- topic bone formation. It is exceedingly rare in colorectal cancer, with an incidence of 0.15% (33 cases reported since 1992). We present a case of osseous metaplasia in colonic adenocarcinoma and review the relevant literature. Methods: A 70-year-old male without any specific peculiar history presented with complaints of abdominal pain and con- stipation. The laboratory results revealed anaemia and elevated inflammatory markers. A computed tomography showed focal asymmetric and irregular thickening of the transverse colon along with regional adenopathy. The patient underwent an extended right hemicolectomy. Results: A fungating firm tan-brown tumour measuring 3.5 cm in the direction of maximum dimension with serosal invasion was identified on gross examination. Microscopic features were that of a gland-forming tumour with focal cribriform architecture and central necrosis. The tumour stroma contained scattered trabecular bone lamellae of variable size outlined by osteoblasts and osteoclasts with- out pleomorphic stromal cells or atypia. Calcifications, bone marrow or cartilage formation were not observed. Mismatch repair protein expression was normal. The tumour was diagnosed as stage IIIB (T4a, N1b, M0) colon carcinoma. Six months after the operation, the patient was still alive and free of local recurrence. Conclusion: Although colorectal cancer is one of the most common cancers, the finding of intratumoural osseous metaplasia is rare. It is important to recognize it in order to avoid misdiagnosis, as it may resemble soft tissue neoplasms or bone invasion. Although there is insufficient data, it seems to have no clinical or prognostic significance. Further research is needed to elucidate the mechanisms involved. E-PS-06-035 Volume of resected tumour as indicator of colorectal cancer dynamics A. Filin*, V. Danilenko, E. Chupandina *Voronezh State Medical University, Russia Background & objectives: Despite the improvement of early diag- nostic methods, late–stage colorectal cancer is diagnosed in more than 25% of patients. Thus, the problem of detecting early stages and detect- ability of colorectal cancer as a whole remains unresolved. Methods: Data from 527 patients suffering from colorectal can- cer who underwent primary tumour resection. Based on the data obtained from the description of the removed intestinal fragments, the volume of the tumour was calculated. The dynamics of changes in tumour volume in patients suffering from colon cancer was stud- ied taking into account the age groups of patients. Results: In the studied material, the tumour volumes varied sig- nificantly: from 0,1 cm3 to 1650 cm3 (average volume 37,3 cm3). In all the studied age periods, the incidence of tumours of differ- ent volumes was similar. The largest and smallest neoplasms are less common, in 3,5% and 4,6% of cases, respectively. It can be assumed that tumours with a small volume are not often found due to rapid progression, and after reaching a certain volume (16-32 cm3, the diameter of such foci varies between 2.5-3.5 cm), their growth is significantly inhibited and only in a few cases tumours grow to gigantic sizes. Conclusion: The change in tumour volume in colorectal cancer occurs non-linearly, explosively. Tumours with a small volume are rare in patients in different age groups. This may be due to their rapid tumour growth. Such an active progression of tumours may explain the low rates of tumour detection in the early stages. E-PS-06-036 Multiple peritoneal calcifying fibrous tumour: a case report S. Makni*, S. Ben Tekaya, M. Mellouli, M. Triki, I. Saguem, S. Charfi, T. Boudawara, M. Manai *Habib Bourguiba University Hospital, Tunisia Background & objectives: Calcifying fibrous tumour (CFT) is a rare benign mesenchymal tumour. The majority are solitary lesions, cases of multifocal tumours are extremely rare. We report a case of multifocal peritoneal CFT in order to discuss histopathologic features and differential diagnosis. Methods: A 25-year-old woman, presented with multiple peri- toneal nodules and a left ovarian mass. Left oophorectomy with excisional biopsy of two nodules were performed, in front of a radi- ological suspicion of malignant ovarian tumour with peritoneal car- cinosis. Macroscopically, the gross nodule was well-circumscribed, measuring 5x4,5x4,5 cm. The surface cuts were gray-white fas- ciculated. The left ovariectomy contains two haemorrhagic cysts. Results: Histopathologically, the nodules consisted of well cir- cumscribed, unencapsulated, abundant paucicellular, hyalinized collagenous tissue. That contain bland spindle cells with a sparse lymphoplasmatic infiltrate and lymphoid aggregates. There was neither cellular atypia nor mitotic figure. Multiple foci of calcifica- tion were scattered throughout the lesions. Immunohistochemical staining showed a positivity with CD34 while AML, H-Caldesmon, S226