GATA3 was positive in all extramammary Paget disease cases tested (13 cases), and it has no value for differentiating between primary and secondary vulvar Paget disease from the urological tract. HER2 amplification might confer an aggressive and invasive pattern in primary vulvar Paget disease, as both amplified cases showed an invasive pattern.

The importance of recognizing osteogenic melanoma is based on difficulties for histologic recognition and its differentials diagnosis.

Follicular dendritic cell (FDC) tumor is an uncommon neoplasm. It generally presents as a slow-growing, painless mass, without systemic symptoms. Histological features usually include low grade spindle cell proliferation. This tumor occurs primarily in lymph nodes, especially cervical and axillary, however, involvement of extranodal sites such as the tonsils, spleen, liver, and gastrointestinal tract has been reported. Inflammatory pseudotumor-like follicular dendritic cell tumor (IPT-like FDCT) is a rare, distinctive histological subtype of this low-grade malignant neoplasm, with consistent Epstein-Barr virus (EBV) association. The differential diagnosis with other fibro-inflammatory tumor proliferations, as inflammatory pseudotumor (IPT) and inflammatory myofibroblastic tumor (IMT), may be challenging. In the present article, two cases of IPT-like FDCT of the spleen are presented, with a broad overview of the literature: one 77-year-old male and one 70-year-old female. A large immunohistochemical panel should be used for diagnosis, as no single specific and totally sensitive markers are available, including markers for CD21, CD23, CD35, CNA42, and clusterin. Individual cases may express one or more of these markers, so that all of them should be investigated. In situ hybridization for EBV is constantly positive. Immunostaining for ALK should be negative, as it is present in roughly half of the cases of IMT. This panel should be used in combination of clinical, laboratory, and topographic evidences. Importantly, inclusion of this lesion as a possible option in clinical and pathological investigation represents the basis for a correct diagnosis.

855 Background: The rate of primary resistance to modern first line (FL) chemotherapy regimen in the treatment of metastatic colorectal cancer (mCRC) is low. Progression Disease (PD) to FOLFOX in the FL is less than 15% in most trials. Prognostic factors associated with worse outcome in mCRC have been identified. However, primary resistance to Oxaliplatin (PROX) containing regimen is not well understood, as well as the role of salvage therapy in further lines of treatment. The aim of the study was to analyze clinical and pathological characteristics of patients with PROX. Methods: A retrospective, single center study included patients that presented PD in the first response evaluation with an Oxaliplatin containing regimen in the FL treatment of mCRC. We also evaluated the Overall Survival (OS) and progression free survival (PFS) of these patients to second and third line. Clinical and pathological variables were analyzed and correlated with (OS). Results: A total of 55 patients were inclued. Median age these cohort was 57 years. Female/Male rate was 42%/58%. Mucinous component was 27%. Right and Left colon was 27% and 66%, respectively. BRAF mutation (2/16 pts). Wild type KRAS was 44%. Synchronic metastasis was 75%. Ressection of metastasis was performed in 20%. Liver limeted disease was found in 45%. Main chemotherapy regimen containing oxaliplatin was FOLFOX (78%) in first line. Bevacizumab, Cetuximab and Panitumumab were used in 21.8%, 9%, 1.8%, respectively. OS was 9.4 months. PFS in second line 3.8 months (47 pts) and third line 3.5 months (18 pts). The only variable associated with longer survival was resection of metastasis (25.6 x 8.6 months, p=0.039). Conclusions: No clinical and pathological variable were able to predict primary resistance to Oxaliplatin containing regimen. However, we found a higher proportion of mucinous subtype. Patients submitted to resection of metastasis had almost three fold the survival of patient that did not underwent surgery. Refractory patients have a very short survival. Further lines of treatment are not able to rescue these patients. Further studies focusing in patients with primary resistance to chemotherapy in first line are needed.

LAMEP) tem o intuito de promover discussões sobre as potencialidades do tratamento personalizado por meio de técnicas moleculares. A LAMEP começou suas atividades no início de 2020, mas em virtude do cenário da pandemia de COVID-19, precisou adaptar-se à modalidade do ensino a distância. Compreendendo que o contexto pandêmico seria prolongado, os ligantes decidiram buscar métodos alternativos de complementação de conhecimento. Foram promovidos encontros para capacitação interna dos ligantes, enquanto que outros foram transmitidos via streaming, na presença de palestrantes. Desde de sua criação, a LAMEP constantemente visa a produção de conteúdo online, no intuito de fomentar a divulgação científica sobre os avanços da Medicina de Precisão.