ECP 2023 Abstracts

S186 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 The tumour involves mostly the fingers, toes, hands and can be subun- gual, with sizes ranging from 0.8 to 5.6 cm. The differential diagnosis includes: extraskeletal osteosarcoma, exostosis, MO, bizarre parosteal osteochondromatous proliferation (Nora lesion). In one study, 80% harboured USP6 rearrangements showing that FOPD belonged to the spectrum of clonal transient neoplasms including: aneurysmal bone cyst, nodular fasciitis, MO and giant cell lesion of small bones. Conclusion: We have presented a rare case of fibro-osseous pseudotu- mour of the digit arising mainly in fingers and toes of young patients. Histologically it is a dermal/soft tissue tumour showing a combina- tion of spindle cells, myxoid stroma, trabecular bone, cartilage and osteoblasts, lacking zoning and without significant atypia. Treatment is by local excision and it rarely locally recurs. It can mimic MO but it is important not to confuse it with osteosarcoma which arises in older patients. Imaging may be helpful. E-PS-05-027 B-cell pseudolymphomatous scarring alopecia due to cutaneous discoid lupus erythematosus, a case report and review of literature F. Kubba*, F. Teixeira, D. Schulman, K. Naresh *Department of Histopathology, Ealing Hospital, London North West University Healthcare NHS Trust, Middlesex, United Kingdom Background & objectives: A 76-year old female with history of osteo- arthritis presented with a 2 cm crusted lesion on the vertex surrounded by and 5 cm area of scarring alopecia. Basal cell carcinoma was sus- pected. She underwent a surgical excision and primary closure. Methods: Microscopy: The skin showed focal ulceration with a dense inflammatory cell infiltrate in the mid-deep dermis sparing the epider- mis and involving the subcutis, forming lymphoid follicles with ger- minal centres. The infiltrate included small lymphocytes, plasma cells and occasional eosinophils. The edge showed a perifollicular/interfol- licular lichenoid infiltrate, surrounding the isthmus and infundibulum of the hair follicles with thickened basement membrane zone. Results: No obvious mucin deposition was seen on Alcian blue. On immunohistochemisty, the follicle centre cells expressed CD10, CD20, IgD (weak) and BCL6. They were negative for BCL2, CyclinD1 and CD5. Ki67 was high, highlighting zonation. Plasma cells expressed MUM1 and were poly- typic for light chain expression. Our working diagnosis was a B-cell pseudolymphomatous scarring alo- pecia caused by cutaneous discoid lupus erythematosus (DLE). A true follicular lymphoma was excluded clinically and histopathologically. On review of the literature, we found cases of cutaneous B-cell lym- phoma arising in longstanding systemic lupus erythematosus, lupus tumidus mimicking primary cutaneous marginal zone B-cell lymphoma and cases of lichenoid cutaneous lupus erythematosus-lichen planus overlap syndrome. Conclusion: We have presented an elderly woman who had histologi- cal features of a B-cell pseudolymphomatous scarring alopecia in the vertex with features of active DLE in the periphery. This is regarded as a complication of longstanding DLE. A punch biopsy from the active edge as well as the central ulcer also may have carried a good diagnos- tic yield. It is important in cases of tumours arising in longstanding DLE to exclude a true cutaneous B-cell lymphoma clinically and on histopathology. E-PS-05-028 Lupus profundus of the scalp associated with nonscarring alopecia, skin plaques and rheumatoid arthritis in a young Afro-Caribbean man, an unusual case report necessitating a multidisciplinary team approach F. Kubba*, A. Jay, R. Agrawal, M. Ratynska, C. Martyn-Simmons, A. Liyadipita, N. Kalavrezos, E. Calonje *Department of Histopathology, Ealing Hospital, London North West University Healthcare NHS Trust, Middlesex, United Kingdom Background & objectives: A 26 year old Afro-Caribbean male with recent history of rheumatoid arthritis (RA) and systemic lupus erythe- matosus (SLE), presented in rheumatology clinic with bilateral raised erythematous, non-itchy lumps on scalp with nonscarring alopecia and plaques on the shoulder and back. Methods: The first two scalp punch biopsies were nondiagnostic, followed a year later by a large 4 cm x 2.5 cm deep skin exci- sion, including the galea aponeurotica, which showed perivascular/ perifollicular superficial and deep dermal/subcuticular lympho- histiocytic aggregates. Alcian blue and colloidal iron highlighted widespread mucin depostion. The epidermis showed no evidence of basal cell apoptosis, interface dermatitis or basement membrane thickening. Results: Most of the lymphocytes in the infiltrate were T cells (CD3+); predominantly(CD4+) with less (CD8+). CD123 showed aggregates of plasmacytoid dendritic cells. Diagnosis: Lupus profundus of the scalp associated with SLE and RA. The superficial biopsies suggested vasculitis and the diagnosis was missed twice due to the shallow sampling. Wide excision was under- taken to exclude a tumour or lymphoma. Lupus profundus (lupus panniculitis) of the scalp is a rare presenta- tion of chronic cutaneous LE. It is found in 1–3% of patients with SLE and can be associated with linear, arched or annular alopecia along Blaschko’s lines. It responds well to treatment with oral prednisolone and hydroxychloroquine, with intralesional triamcinolone acetonide injections. Conclusion: We have presented a rare case of lupus profundus of the scalp, associated with nonscarring alopecia and skin plaques in the shoulder and back. The initial punch biopsies suggested vasculitis and failed to nail the diagnosis due to the superficial sampling. The patient ended up with a large excision to achieve the final diagnosis. This presentation shows the importance of multidisciplinary approach in this unusual site and supports the need of a deep incisional biopsy from the first instance. E-PS-05-029 Acute extensive and advanced stage Marjolin’s ulcer arising within a below knee amputation stump ulcer in a middle-aged man, a case report and review of literature F. Kubba*, I. Logan, B. Gaglani, P. Baghla *Department of Histopathology, Ealing Hospital, London North West University Healthcare NHS Trust, Middlesex, United Kingdom Background & objectives: A 55-year-old Asian male was admitted with an infected ulcer of a right below knee amputation stump. A mid- tibial amputation had been performed following a traumatic injury 8 months previously. Past medical history: hypertension, non-alcoholic fatty liver disease and hyperlipidaemia. Methods: On examination there was an extensive large fungating tumour/ulcer of the entire stump measuring 21x13cm with hypergran- ulating indurated margins. Multiple 1-2 cm groin lymph nodes were palpable. Features were those of a Marjolin’s ulcer. MRI scan of the right knee showed high-signal enhancement of soft tissues. CT scan chest/abdomen/pelvis showed bilateral inguinal lym- phadenopathy. An above knee amputation was completed. Results: Microscopy: Invasive moderately differentiated squamous cell carcinoma(SCC) of no special type, invading 75mm into the subcutis and fibula and consuming neurovascular bundles; stage pT4a pN0 pMx with free resection margins. At 10 month follow-up: No evidence of locoregional recurrence or distant metastasis.