ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 the concentric layers. Our case is consistent with the acanthotic variant of OCM. At 1-year follow-up, there was no recurrence. Conclusion: Only 17 cases of OCM have been reported in the English literature until 2020. Clinically it shows a localized thickening of the nail plate and a longitudinal band. Histologically, the characteristic feature is acanthosis of the nail matrix and nests of prekeratogenous and keratog- enous cells with variation in their components. Four histological types can be identified: acanthotic, acanthotic and papillomatous, keratogenous with retarded maturation and germinotropic. OCM should be included in the differential diagnosis of clinically longitudinal nail bands. E-PS-05-027 Merkel cell carcinomas associated to a primary haematological neoplasm: a unique case associated to follicular lymphoma E. Miraval Wong*, P. Puente Lopez, E. García Fernández *Hospital Universitario La Paz, Spain Background & objectives: Merkel cell carcinoma (MCC) has been associated with primary haematological neoplasms due to immune dys- function and MCPyV reactivation. We did a 30-year review of MCC in association with a lymphoproliferative disorder and described a patient with follicular lymphoma. Methods: We identified biopsies of cases of MCC using SNOMED coding lists from 1992 to 2022. We found 58 patients with MCC; after- ward we reviewed patient history to detect associated haematological neoplasms. We describe histopathological, immunohistochemical and molecular diagnosis of Follicular Lymphoma (FL) with MCC. Results: Fifty-eight patients were diagnosed with MCC in the last 30 years of whom 3 (5.2%) had an haematological neoplasm (chronic lym- phocytic leukaemia, mycosis fungoides and FL). A 57 years-old man was diagnosed with FL grade 1-2. He was treated with R-CHOP and kept with rituximab maintenance. After 8 months of complete remis- sion, he developed a 5 cm cutaneous nodule on his left arm. Resection specimen showed cutaneous infiltration of MCC and a close lymph node with a FL grade 1-2 (positivity for CD20, BCL-2, CD10 and BCL-6) and MCC metastasis. The sentinel lymph node had the same features and was positive for BCL-2 translocation. Conclusion: MCC can associate a haemato-oncological neoplasia being chronic lymphocytic leukaemia the most frequent. There is only one case described in the literature with a FL and a secondary MCC, which appeared 10 months after the remission with rituximab treatment. Unlike our case, the reported one did not have a FL relapse. There can be overlapping marker expression between MCC and haematological neoplasms like our case that was positive for BCL-2 in both of them, creating potential pitfalls. E-PS-05-028 VEXAS: case report and characteristics of a new syndrome with neutrophilic dermatosis G. Barrios Millán*, G. Servera, E. Sendagorta, E. García Fernán- dez, E. Ruiz-Bravo, M.J. Beato *La Paz University Hospital, Department of Pathology Spain Background & objectives: VEXAS is acronym for Vacuoles, E1 enzyme, X-linked, Autoinflammatory and Somatic mutation. Its cause is a somatic mutation in UBA1, a gene that encodes for E1 ubiquitin activating protein. We present a new case of this very recently described entity. Methods: For the case report we searched the patient’s electronic medical records from 2012, when symptoms started, to 2021, when diagnosis was made, including subsequent follow-up to date. For the literature review we searched Pubmed. Results: In 2012, a 58-year-old male had skin lesions that were diagnosed as lupus erythematosus. Along the course of the disease he presented arthralgias, serositis, anaemia, thrombocytopenia, and pancytopenia. This led to a bone marrow biopsy and aspirate, that showed a myelodysplastic syndrome with vacuoles. In 2021 showed er ythematous papules and plaques that, when biopsied, exhibited neutrophils t hat were located i n d e r mi s a nd a d i pou s t i s s u e . VEXAS s ynd r ome wa s s u s p e c t e d , a nd ge n et i c st udy c on f i r me d t h e mu t a t i on in UBA1 gene. Detection of t he causing mut ation was revolutionar y because the method used star ted with the analysis of numerous mapped genomic sequences, in which the common f indings in UBA1 led with similar clinical findings. Conclusion: VEXAS syndrome was described at the end of 2020. It’s to be suspected in older males with a combination of inflammatory signs like refractory fever and polychondritis, as well as hematologic alterations. Vacuoles in myeloid and erythroid precursor cells of bone marrow biopsy are characteristic. In the skin, causes several lesions that, in the biopsy, show a neutrophilic dermatosis. Since its description, VEXAS syndrome has explained many cases that had failed to be classified in any of the known diseases. E-PS-05-029 Nivolumab therapy in multiple primary melanomas – a case report A. Cohn*, A.D. Chirita, A. Alexandru, O. Repede, I. Margaritescu *Emergency University Hospital, Bucharest, Romania Background & objectives: Melanoma is a cutaneous malignancy that may benefit from immune therapy with checkpoint inhibitors, even in advanced stages. We report a case with two primary melanomas treated with nivolumab, highlighting the histopathological findings and the clinical evolution. Methods: A 70-year-old man presented to the dermatologist for alopecia, when a large infiltrative tumour located on the scalp and a second pigmented lesion on the cheek were discovered. Computed tomography examination revealed that the scalp tumour was infil- trating the occipital bone, extending close to the superior sagittal sinus. As the neoplasm was unresectable, punch biopsies from both lesions were performed. Results: The lesion on the cheek was diagnosed as melanoma in situ. Scalp biopsy showed a desmoplastic melanoma com- posed of a dermal fascicular proliferation of spindle cells, positive for Sox-10 and S100. BRAF molecular studies were negative. As desmoplastic melanoma is reported to respond well to immunotherapy, PD-L1 immunostaining was done, showing diffuse positivity in tumour cells. The patient was enrolled in a clinical study receiving NKTR and nivolumab (10 cycles). Given his renal disease, he then remained only on nivolumab. At follow-up, a spectacular decrease in meas- urements was noted in both lesions. The tolerability profile was acceptable and lesions have been stable for the past 6 months. Conclusion: This study presents the impressive clinical evolution of a locally aggressive inoperable desmoplastic melanoma with significant shrinkage in size, associated with a tolerable toxicity profile. As the patient has a stable response to nivolumab with no imaging progression, anti-PD-1 therapy has promising results in increasing the overall survival and reducing the risk of metastases in advanced-stage melanoma. S213