ECP 2023 Abstracts

S249 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Background & objectives: Thyroid carcinoma patients benefit from recently approved treatments, such as tyrosine kinase inhibitors. These are used in patients at progression but in few cases, they have been used before primary surgery. There is little data regarding histopathological effects on thyroid. Methods: Our patient is an 89-year-old woman with a locally advanced thyroid papillary carcinoma BRAF-V600E mutated. The Multidiscipli- nary Team dismissed surgical treatment due to extensive invasion, and decided to start lenvatinib, a kinase inhibitor. After three months, treatment was interrupted due to secondary effects. The CT-scan showed tumour size reduction associated with necrosis. Then, total thyroidectomy and central lymphadenectomy was performed. Results: Thyroidectomy specimen was firm. At sections, three differ- ent areas were identifiable. One central area partially encapsulated with intermixed white and yellow tissues. Another adjacent fleshy region. And a third peripheral white firm section. At microscopy, the central area was mainly composed of loose fibrous tissue intermixed with hyalinised mate- rials. There were scant vessels, calcifications, slight lymphoplasmacytic infiltrates and cholesterol-associated granulomatous reactions. There were isolated follicle neoplastic glands remaining in this section. The fleshy region was an area of conventional papillary carcinoma. Whereas the peripheral region was composed of papillary carcinoma with conventional morphology and an increased mitotic index (11 mitosis/2mm2), consistent with high grade follicular cell-derived thyroid carcinoma. Conclusion: In our specimen, we identified areas suggestive of tumour regression after treatment adjacent to areas of high-grade neoplasm. We cannot discern whether this high-grade component was present before target therapy or if it was developed following therapy pressure. As pathologists, we should collect these cases to further clarify this issue and to propose a neoadjuvant response measurement system. E-PS-09-018 Sarcoidosis and thyroid autoimmunity: a rare case of concomitant Graves’ disease and thyroid sarcoidosis P. Radia*, R. Simo, L. Collins *Guys and St Thomas’ Hospital, United Kingdom Background & objectives: Autoimmune thyroid diseases (AITD) can be associated with other systemic or organ specific autoimmune diseases. Up to 20% of patients with sarcoidosis present with AITD. However, involvement of the thyroid gland with sarcoidosis is rare and can make management challenging. Methods: We present the clinical and pathological findings of a patient with concomitant Graves’ disease and sarcoidosis of the thyroid gland. Results: A 46 year old woman presented with trismus and heart palpita- tions. Laboratory studies showed thyrotoxicosis, consistent with Graves’ disease. Her medical history included fatty liver disease and sarcoid. The patient was started on carbimazole PTU and reached a suppressed TSH and T4 of 49 mIU/mL. After developed a hypersensitivity reaction, the drug had to be stopped. Although alternative anti-thyroid drugs were administered, the patient required a total thyroidectomy. Histopathological examination of the thyroid gland showed features compatible with Graves’ disease with florid non-necrotizing granu- lomatous inflammation. Special stains for fungal organisms and acid fast bacilli were negative. With the clinical findings, a diagnosis of Graves’ disease with thyroid sarcoidosis was made. Conclusion: Autoimmune thyroid disease is commonly seen in patients with sarcoidosis. Involvement of the thyroid gland itself with sarcoid is rare but should be considered in patients with medication unresponsive disease as it may lead to resistance of anti-thyroid drugs. E-PS-09-019 An unusual location for a malignant epithelioid PEComa: the adre- nal gland D. Sá*, J.R. Brandão, F.S. Vieira, G. Carrola *Centro Hospitalar Universitário de Santo António, Portugal Background & objectives: PEComa (perivascular epithelioid cell tumour) is a mesenchymal tumour composed of perivascular epithe- lioid cells, and it occurs more frequently in the uterus and retroperito- neum. To our knowledge, there are fewer than ten reported cases arising in the adrenal gland. Methods: We herein report a case of a 57-year-old woman with a 5-month history of fever, asthenia, and weight loss. During workup, a CT scan was done which revealed a right adrenal mass measuring 11cm of maximum dimension. Adrenal hormone tests were unremarkable, hence proving this was a non-secretory tumour. An adrenalectomy was then performed to characterize this lesion. Results: We received a right adrenalectomy specimen almost totally occupied by a multinodular 13cm neoplasm, poorly delineated from the adjacent parenchyma, displaying a white cut surface and haemorrhagic areas. Histologic examination showed an infiltrative neoplasia present- ing a solid or fascicular pattern and composed of epithelioid or rarely spindle cells with eosinophilic cytoplasm, elongated to ovaloid vesicu- lar nuclei with prominent nucleoli. There were also areas of necrosis, vascular invasion, multinucleated giant cells, and a high mitotic rate with atypical mitotic figures. Immunohistochemistry revealed expres- sion of HMB-45 and MelanA diffusely and SMA in the spindle cell component, with negativity for CAM5.2, Calretinin, Inhibin, Synapto- physin, Chromogranin, S100, SOX10, Desmin, MDM2, CAIX, PAX8 and TFE3. Conclusion: Epithelioid PEComa can pose a diagnostic challenge as it can be difficult to distinguish from other tumours. High-risk criteria for malignancy in non-gynaecologic PEComa include having > 5 cm, a mitotic rate > 1/50 HPF, necrosis, a high nuclear grade and cellularity, vascular invasion, and an infiltrative growth pattern. If two or more features are present, as in our case, these tumours should be consid- ered malignant. The patient currently has no evidence of recurrence or metastasis 6 months after surgery. E-PS-09-020 Parathyroid carcinoma: a case report A. Sifre-Ruiz*, È. Iglesias Martínez, N. Santiago-Quispe, M.M. Buda, C. Esquina, A.M. Cordovilla-Moreno, M. Bronte-Anaut *Clinical Department Unit of Pathological Anatomy, OSI Araba, Araba University Hospital. Bioaraba Health Research Institute, Vitoria- Gasteiz, Alava, Spain Background & objectives: Parathyroid carcinoma (PC) is a rare neo- plasm, which can be either sporadic or associated with familial hyper- parathyroidism related syndromes. The majority of them are function- ing tumours representing <1% of primary hyperparathyroidism. Methods: The histologic sections of a case of PC diagnosed in our centre in 2023 were reviewed. To verify the diagnosis, organ-specific staining (PTH) and vascular endothelial staining (CD31) were per- formed. In addition, the clinical data and personal and family history of the patient were reviewed and summed up. Results: We report the case of a 56-year-old man diagnosed with pri- mary hyperparathyroidism (serous calcium levels 12.6 mg/dl) with an anterior cervical node, who underwent a surgical excision. In the mac- roscopic study, we found a nodular and heterogeneous solid lesion that corresponded to a densely cellular capsulated tumour, composed by medium-sized eosinophilic cells arranged in solid nests, trabeculae and occasional follicles, separated by fibrous septa. The cellular population presented mild anisonucleosis, evident nucleolus and clumpy chro- matin and expressed PTH. Multiple images of vascular invasion were identified, but no intratumoral necrosis was observed. After diagnosis, the patient was referred to the Genetics Department. Conclusion: PC is a rare neoplasm that can occur at any age (mean age at time of diagnosis 51-57 years). The majority are functioning