ANNUAL MEETING ABSTRACTS

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1 ANNUAL MEETING ABSTRACTS 453 Do Cutaneous Leiomyomas Have Similar Morphological and Molecular Alterations to Uterine Tumors in the Hereditary Leiomyomatosis and Renal Cell Cancer Syndrome (HLRCC)? LY Ballester, PP Aung, K Lara-Otero, WM Linehan, MJ Merino. NIH/NCI, Bethesda, MD. Background: HLRCC is an autosomal dominant syndrome characterized by the development of cutaneous and uterine leiomyomas (CL) and renal cell carcinoma (RCC). It has been associated to mutations in the fumarate hydratase gene, in chromosome 1q42-1q43. Loss of heterozigosity (LOH) in this region is evident in the RCC that develop in these patients. Uterine leiomyomas are frequently found in females with HLRCC, the tumors show LOH in 1q42-1q43 and have a histological appearance distinct from the sporadic leiomyomas (i.e. higher cellularity, eosinophilic nuclei, prominent nucleoli with perinuclear halos and mitosis). CL have been observed in 76% of families with HLRCC, presenting as firm skin-coloured to light brown-coloured papules and nodules predominantly in the chest and arms of the patients. Design: To describe the morphology of CL in HLRCC and assess if they differ from their sporadic counterparts and if they share morphological and molecular characteristics with uterine leiomyomas. We examined the histological features (circumscription, atypia, mitosis, necrosis, size, nuclear morphology, MIB1 labeling, presence of inflammation) of 100 CL of patients with HLRCC syndrome. Tumors and normal tissues were microdissected and DNA extracted for LOH analysis of the 1q42-1q43 region. Results: The mean age of the patients was 45.2 years with 66% of the patients being female and 34% males. The most common tumor locations were the arm/forearm (51%), back (30%), chest (11%) and other (4%). The tumors were well-circumscribed and localized to the dermis with a Grenz zone. The mean tumor size was 0.34 ± 0.01 cm. The tumors contained interlacing fascicles of smooth muscle cells with elongated nuclei and abundant eosinophilic cytoplasm. None of the lesions showed the atypical features present in uterine leiomyomas. LOH analysis showed loss of heterozigosity for the 1q42-1q43 region in several of the tumors, similar to the uterine leiomyomas. Conclusions: Our findings suggest that in HLRCC patients, the CL have the so called second hit present in renal tumors and uterine leiomyomas, as evidenced by LOH for 1q42-1q43. However, even when cutaneous leiomyomas share the similar LOH present in uterine leiomyomas, they do not show the characteristic atypical morphologic features of uterine tumors. These findings suggest that other alterations, besides LOH for region 1q may play an important role in the development of leiomyomas in HLRCC patients. 454 Morphogenesis and Fibrogenesis Pathways for the Distinction of Slerosing Melanocytic Nevus and Desmoplastic Malignant Melanoma A Blanes, L Pozo, SJ Diaz-Cano. University of Malaga School of Medicine, Malaga, Spain; Homerton University Hospital, London, United Kingdom; King s College Hospital, London, United Kingdom. Background: Fibroblastic reaction can be observed in benign and malignant melanocytic lesions and cause serious diagnostic problems. The mechanism of fibrogenesis and the diagnostic utility of fibrogenesis markers have not been investigated in this context. Design: We analyzed symmetry, maturation, growth patterns (nested-trabecular, nodular-solid, diffuse), nuclear grade (including chromatin, nucleolus, pleomorphism and anisokaryosis), stromal reaction, and confluent necrosis in desmoplastic (sclerosing) melanocytic nevi (DMN, 18) and desmoplastic malignant melanoma (DMM, 24), classified according to the WHO criteria. Cases with history of previous excision, trauma or histological scarring were excluded. Representative samples were evaluated by quantitative RT-PCR and standard in situ techniques for morphogenesis and fibrogenesis pathways (fibrinogen, CD34, CTNNB1, FOXC2, JAG1, RAC1, SMAD2, SNAI1, SOX10, TGFB1, TGFB2, TGFB3, TWIST1, WNT11, WNT5A, PDGFA, SPARC, PDGFRA, HSPG2). Appropriate controls were run. Fisher s exact tests and analysis of variance (significant if P<0.05) were used for comparison; significant variables were then selected for discriminant analysis with cross-validation for diagnostic groups (DMN vs. DMM). Results: Fibrinogen expression was found in both DMN and DMM but with different pattern: perivascular stroma in DMN and in tumour cells and blood vessels with a heterogeneous pattern in MM. CD34 was revealed positive in dermal dendritic cells of the sclerosed interstitium of DMN, and in the peritumoural stroma of DMM. PDGFRA was expressed in DMN, but not in DMM and HSPG2 (perlecan protein) revealed significantly higher expression in DMM. The remaining markers revealed no statistically significant differences in the expression by DMN and DMM. Conclusions: The sclerosis seen in DMN is directly correlated with fibrinogen leaking from blood vessels and it is not a destructive process (preserved intratumour CD34 positive cells), whereas the fibrogenesis in MM is secondary to tissue destruction (loss of intratumour CD34 positive cells and increased turnover of HSPG2) and is enhanced by PDGFRA-independent tumour cell expression of fibrinogen. 455 BRAF V600 Mutation Detection by Immunohistochemistry Shows Tumor Homogeneity between Primary and Metastatic Sites L Boursault, V Haddad, T Jouary, B Vergier, S Verdon, A de Mascarel, JP Merlio. CHU et Université, Bordeaux, France, Metropolitan. Background: Metastatic melanoma is associated with a poor prognosis. First line therapy using the BRAFV600E kinase inhibitor increase overal survival of patients with metastatic melanoma and BRAFV600 mutation. Thus, rapid and accurate detection of BRAFV600 mutation is critical in such patients. However, intra or inter-tumor heterogeneity may account for different rates of BRAF mutation detection among differents sites. We have evaluated the potential use of immunohistochemistry(ihc) for detecting BRAFV600 mutations by comparison with molecular detection in a parallel blinded study. Moreover, we also evaluated whether intra and inter tumor heterogeneity may account for discrepancies between primary and metastatic material. 111A Design: We studied 96 metastatic melanoma patients with AJCC stage IIIc or IV, with a total of 221 samples, including primary melanoma(n=86) and different metastatic localization(n=135).braf mutation testing was performed on sections from FFPE material using two techniques: HRM analysis followed by Sanger sequencing of variant profiles and anti-brafv600e immunostaining. Results: As reported by others, IHC was positive in all samples harboring V600E and V600E2 mutations and negative for all other mutations, including V600K(n=3, L597S(n=2), K601E(n=3) and pd594n(n=2). The cytoplasmic staining was either strongly positive in most tumour cells of V600E and V600E2 mutated cases or completely negative. It appeared strong brown with small dots. IHC staining and/or HRM analysis showed a perfect concordance between matched primary melanoma and metastasis.the prevalence of each BRAF mutation was V600E(40.6%), V600E2(3.1%), V600K(1.04%) and others(1.04%) respectively. Concordance between the two techniques was 99,5%. Sensitivity for IHC taking into account all V600BRAF mutations was 97% while specificity was 100%. Conclusions: This study confirms the performance of IHC for BRAFV600E and V600E2 mutation detection using the VE1 antibody positivity. It provide evidence that VE1 IHC may be a cost-effective method of BRAFV600 status assessment, although some cases harbouring the V600K mutation were missed in patients who may benefit from Vemurafenib. Unlike previous reports, IHC was not found more sensitive for BRAFV600E mutation detection than its molecular detection as the two techniques matched perfectly. Moreover, using IHC we report for the first time the concordance between BRAF status at primary and metastatic sites that together with the homogeneous staining observed by IHC would suggest tumour homogeneity rather than heterogeneity at least for this primary genetic alteration. 456 T-Cell Subsets and Plasmacytoid Dendritic Cells in Rosacea and Cutaneous Lupus Erythematosus: A Comparative Immunophenotypic Analysis T Brown, Jr., K Choi, D Thomas, A Hristov, M Chan. University of Michigan Medical Center, Ann Arbor, MI. Background: Distinction of rosacea and cutaneous lupus erythematosus (LE) can be challenging due to clinical and histologic overlaps. Both conditions may present as facial edema or inflammatory papules, and typically demonstrate perifollicular and perivascular T cell-rich infiltrates histologically. Increased CD8+ cytotoxic T cells, decreased CD4+FoxP3+ regulatory T cells (Tregs), and increased CD123+ plasmacytoid dendritic cells (PDCs) have been reported in the skin lesions of LE. Similar data are lacking in rosacea. We hereby explore the utility of immunohistochemistry in differentiating rosacea and LE by comparing their T-cell subsets and the number of PDCs. Design: The surgical pathology archive at University of Michigan was searched for cases of rosacea and facial LE. CD4, CD8, CD25, and CD123 immunostains were performed on all cases. The CD4:CD8 ratio in each case was estimated by counting positive cells on digital images taken of at least one representative lymphoid aggregate. Using the same method, the percentage of CD4+CD25+ regulatory T cells (Tregs) was determined by dividing the number of CD25+ cells by the number of CD4+ cells (CD25/CD4). The percentage of CD123+ PDCs of the total infiltrate was estimated in a semi-quantitative manner (0 to 100% in 10% increments). Any clustering of more than twenty CD123+ cells was also noted. All data were obtained by multiple authors blinded to the final diagnoses. Results: Twenty-seven cases of rosacea and 30 cases of facial LE were selected after careful clinicopathologic review. The mean CD4:CD8 ratio is 2.80 in rosacea and 1.74 in LE (p=0.0272). The proportion of CD25+/CD4+ Tregs is 31% in rosacea and 13% in LE (p<0.0001). The percentage of CD123+ PDCs is 6% in rosacea and 18% in LE (p=0.0008). Clustering of CD123+ cells is seen in 18% of rosacea, and in 60% of LE (p=0.0026). Conclusions: Cases of facial LE show significantly lower CD4:CD8 ratio, fewer CD25+ Tregs, and more CD123+ PDCs than rosacea. These findings support the implication of T cell-mediated cytotoxicity, decreased immune suppression by Tregs, and increased interferon-producing PDCs in the pathogenesis of LE. We propose that these findings may serve as useful adjunctive tools in distinguishing rosacea and LE in difficult cases. 457 Ossifying Fibromyxoid Tumor and Its Non-Ossifying Variant: A Diagnostic Challenge for Dermatopathologists D Buehler, N Atanaskova Mesinkovska, CM McClain, BP Rubin, J Goldblum, SD Billings. Cleveland Clinic, Cleveland, OH; Vanderbilt University, Nashville, TN. Background: Ossifying fibromyxoid tumor (OFMT) is a rare, potentially aggressive, tumor that typically arises in the subcutis. Therefore it is encountered by dermatopathologists and is a source of diagnostic difficulty. In this study, the clinicopathologic features and outcomes of twenty-three subcutaneous OFMT were reviewed. Design: Histologic sections of subcutaneous OFMTs were assessed for the morphologic patterns. Prognostic classification as typical, atypical and malignant OFMT was assigned. Patient and tumor characteristics and follow up information were obtained from institutional records and contributing pathologists. Results: Patients (15 F, 8 M) ranged in age from 26 to 88 years (mean 53 years). The tumors ranged from 0.8 to 8.5 cm (mean 2.7 cm) in size, and all arose in the subcutis of the leg (n=11), trunk (n=7), head/neck (n=3), or arm (n=2). All were well circumscribed with a fibrous pseudocapsule. A partial shell of bone was present in 11 of 23 cases while 12 cases were classified as the nonossifying variant. All had a lobular growth pattern with the tumor cells arranged in combinations of nested, reticular and fascicular patterns. Cellularity ranged from low (n=13) to moderate (n=6) to high (n=4). Mild to moderate cytologic atypia was observed in most cases with more cellular cases demonstrating greater nuclear atypia. The average mitotic rate was 6 per 50 HPFs (range 0-46). 13 of

2 MORPHOGENESIS AND FIBROGENESIS PATHWAYS FOR THE DISTINCTION OF SCLEROSING MELANOCYTIC NEVUS AND DESMOPLASTIC MALIGNANT MELANOMA Alfredo Blanes, Lucia Pozo and Salvador J Diaz-Cano University of Malaga School of Medicine, Malaga, Spain; Homerton University Hospital and King's College Hospital, London, UK Fibrous Reaction in Melanocytic Lesions Fibroblastic reaction can be observed in benign and malignant melanocytic lesions Fibrosis and regression cause serious diagnostic problems The mechanism of fibrogenesis and the diagnostic utility of fibrogenesis markers have not been investigated in this context 1

3 6/4/14 Desmoplasia (sclerosis) is a common morphological change in skin tumors and in some melanocytic tumors The cause of mucin deposition in both DMN and MM is unclear, that could be related with progressive involution of the lesions in DMN or presence of mesenchymal reactive elements in MM* * Rongioletti F. and Innocenzi D. Sclerosing mucinous blue naevus. Br J Dermatol 2003; 148: Sclerosing Melanocytic Nevus Desmoplastic Malignant Melanoma 2

4 Materials and Methods Case selection: Desmoplastic (sclerosing) melanocytic nevi (DMN, 18) and desmoplastic malignant melanoma (DMM, 24), classified according to the WHO criteria Cases with history of previous excision, trauma or histological scarring were excluded We analyzed morphological features: Symmetry, maturation, growth patterns (nested-trabecular, nodular-solid, diffuse), Nuclear grade (including chromatin, nucleolus, pleomorphism and anisokaryosis), Stromal reaction, and confluent necrosis Representative samples were evaluated by Quantitative RT-PCR and standard in situ techniques (CMN -15-, MM -15-, as controls) Morphogenesis and fibrogenesis pathways (fibrinogen, CD34, CTNNB1, FOXC2, JAG1, RAC1, SMAD2, SNAI1, SOX10, TGFB1, TGFB2, TGFB3, TWIST1, WNT11, WNT5A, PDGFA, SPARC, PDGFRA, HSPG2). Appropriate controls were run. Statistical analysis: Fisher's exact tests and analysis of variance (significant if P<0.05) were used for comparison; Significant variables were then selected for discriminant analysis with cross-validation for diagnostic groups (DMN vs. DMM) Fibrinogen Fibrinogen expression was found in both DMN and DMM but with different pattern: perivascular stroma in DMN and in tumor cells and blood vessels with a heterogeneous pattern in MM. 3

5 6/4/14 CD34 CD34 was revealed positive in dermal dendritic cells of the sclerosed interstitium of DMN, and in the peritumoral stroma of DMM. The sclerosis seen in DMN is directly correlated with fibrinogen leaking from blood vessels and it is not a destructive process (preserved intratumor CD34 positive cells and preserved elastic fibers)* These findings correlates the sclerosis seen in DMN with that seen in localized scleroderma** * Camacho NR et al. Medium-dose UVA1 phototherapy in localized scleroderma and its effect in CD34-positive dendritic cells. J Am Acad Dermatol. 2001; 45: ** Falanga V et al. Fibrin and fibrinogen-related antigens in systemic sclerosis (scleroderma). J Am Acad Dermatol. 1991; 25:

6 PDGFRA PDGFRA was expressed in DMN, but not in DMM and HSPG2 (perlecan protein) revealed significantly higher expression in DMM. PERLECAN PDGFRA was expressed in DMN, but not in DMM and HSPG2 (perlecan protein) revealed significantly higher expression in DMM. 5

7 Expression of fibrogenic cytokines in the fibrous stroma of tumors: from benign melanocytic nevi to malignant melanoma* Localization of cytokines in nevi and malignant melanoma** Patterns of expression of these fibrogenic cytokines in normal skin, localized morphea and scars * Kubo M et al. Expression of fibrogenic cytokines in desmoplastic malignant melanoma. Br J Dermatol 1998; 139: ** Fleming M G et al. Immunohistochemical localization of cytokines in Nevi. Am J Dermatopathol 1992; 14: Conclusions The sclerosis seen in DMN is directly correlated with fibrinogen leaking from blood vessels and it is not a destructive process (preserved intratumor CD34- positive cells) Fibrogenesis in MM is secondary to tissue destruction (loss of intratumor CD34-positive cells and increased turnover of HSPG2) and is enhanced by PDGFRA-independent tumor cell expression of fibrinogen 6