Therapeutic outcomes and survival analysis of Extramammary Paget's disease: A multicentre retrospective study of 249 patients.

BACKGROUND: Evidence regarding long-term therapeutic outcomes and disease-specific survival (DSS) in Extramammary Paget's disease (EMPD) is limited. OBJECTIVES: To assess the DSS and outcomes of surgical and nonsurgical therapeutic modalities in a large cohort of EMPD patients. METHODS: Retrospective chart review of EMPD patients from 20 Spanish tertiary care hospitals. RESULTS: Data on 249 patients with a median follow-up of 60 months were analyzed. The estimated 5-, 10-, and 15-year DSS was 95.9%, 92.9%, and 88.5%, respectively. A significantly lower DSS was observed in patients showing deep dermal invasion (≥1 mm) or metastatic disease (P < .05). A ≥50% reduction in EMPD lesion size was achieved in 100% and 75.3% of patients treated with surgery and topical therapies, respectively. Tumor-free resection margins were obtained in 42.4% of the patients after wide local excision (WLE). The 5-year recurrence-free survival after Mohs micrographic surgery (MMS), WLE with tumor-free margins, WLE with positive margins, radiotherapy, and topical treatments was 63.0%, 51.4%, 20.4%, 30.1%, and 20.8%, respectively. LIMITATIONS: Retrospective design. CONCLUSIONS: EMPD is usually a chronic condition with favorable prognosis. MMS represents the therapeutic alternative with the greatest efficacy for the disease. Recurrence rates in patients with positive margins after WLE are similar to the ones observed in patients treated with topical agents.

Dermatofibrosarcoma Protuberans: A Study of 148 Patients.

INTRODUCTION: Dermatofibrosarcoma protuberans (DFSP) is the most common sarcoma of the skin. Although distant metastases are infrequent, DFSP is highly aggressive locally with frequent local recurrences. It has been reported that the presence within the tumour of areas histopathologically mimicking fibrosarcoma may increase the risk of recurrence. OBJECTIVE: The objective of this study was to review the clinical features of our patients with DFSP and the factors associated with recurrence of the tumour, focussing on the presence of fibrosarcomatous areas. METHODS: Retrospective study of patients with DFSP diagnosed in 1990-2021 in a tertiary university hospital. The medical records were reviewed to obtain the following data: age, sex, tumour location, diameter, evolution time, presence of fibrosarcomatous areas, development of recurrence, and follow-up. Factors possibly associated with disease-free survival were analysed with Kaplan-Meier method and multivariate Cox regression. RESULTS: 148 patients (74 women/74 men, mean age 46.28 years, SD 14.431) were included in the study. Tumours involved the head and neck in 15 cases, thorax in 31, abdomen in 16, upper back in 43, lower back in 10, upper extremities in 10, and lower extremities in 23. Fibrosarcoma-like areas were observed in 16 tumours (10.81%). In 17 patients (11.49%), recurrences were observed (13 local recurrences, 3 lung metastasis, and 1 local recurrence with lung metastasis). Fibrosarcomatous DFSP recurred more frequently than classic DFSP (50% vs. 6.82%, respectively), and its disease-free survival was significantly lower (p < 0.001). In multivariate Cox regression, the presence of fibrosarcomatous areas was the only factor influencing disease-free survival. CONCLUSIONS: It is important to identify the fibrosarcomatous variant since it recurs more frequently and has lower recurrence-free survival. Distant metastases, mainly in the lung, are also more frequent in fibrosarcomatous DFSP.

Treatment of extramammary Paget's disease with imiquimod in a real-life setting: a multicenter retrospective analysis in Spain.

BACKGROUND: Topical imiquimod has shown to be an effective treatment for EMPD, although available evidence supporting its use is based on case reports and small series of patients. OBJECTIVES: To investigate the therapeutic outcomes and analyze potential clinico-pathological factors associated with imiquimod response in a large cohort of EMPD patients. METHODS: Retrospective chart review of 125 EMPD patients treated with imiquimod at 20 Spanish tertiary-care hospitals. RESULTS: During the study period, patients received 134 treatment regimens with imiquimod, with 70 (52.2%) cases achieving complete response (CR), 41 (30.6%) partial response and 23 (17.2%) no response. The cumulative CR rates at 24 and 48 weeks of treatment were 46.3% and 71.8%, respectively, without significant differences between first-time and previously treated EMPD. Larger lesions (≥6 cm; p = 0.038) and EMPD affecting >1 anatomical site (p = 0.002) were significantly associated with a worse treatment response. However, the CR rate did not differ significantly by the number of treatment applications (≤4 vs. > 4 times/week; p = 0.112). Among patients who achieved CR, 30 (42.9%) developed local recurrences during a mean follow-up period of 36 months, with an estimated 3 and 5-year recurrence free-survival of 55.7% and 36.4%, respectively. CONCLUSIONS: Imiquimod appears as an effective therapeutic alternative for both first-line and previously treated EMPD lesions. However, a less favorable therapeutic response could be expected in larger lesions and those affecting >1 anatomical site. Based on our results, a 3-4 times weekly regimen of imiquimod with a treatment duration of at least 6 months could be considered an appropriate therapeutic strategy for EMPD patients.

Leishmaniasis in otorhinolaryngology: an emerging disease and its relationship with anti-tumor necrosis factor-alpha drugs.

PURPOSE: To investigate the clinical manifestations, management and outcomes of Leishmania lesions in the ear-nose-throat (ENT) region, and its relationship with tumor necrosis factor (TNF)-α blocking drugs. METHODS: Single-center retrospective observational study. Patients diagnosed with cutaneous and mucosal leishmaniasis in the otorhinolaryngologic area at a tertiary referral center over a period of 8 years. RESULTS: Three cases of Leishmania lesions in the ear and two in the nose were encountered at our institution. All patients were under treatment with TNF-α blocking drugs. Diagnosis was challenging, and it was important to have a clinical suspicion in order to use accurate detection techniques. All patients received systemic treatment and achieved a complete resolution of the lesions. CONCLUSIONS: With the increasing use of biologic treatments like TNF-α blockers, this type of infection will be increasingly frequent in endemic areas and also worldwide. It is important to include leishmaniasis in the differential diagnosis of inflammatory/infectious lesions in the ENT region.

Cutaneous Leiomyoma: A Clinical Study of 152 Patients.

BACKGROUND: Cutaneous leiomyoma (CL) is a benign smooth muscle tumour included in painful skin tumours. Multiple CLs are cutaneous markers of hereditary leiomyomatosis and renal cell cancer (HLRCC). OBJECTIVES: To retrospectively review our series of patients with CLs to analyse their clinical features and the association with HLRCC. METHODS: Cases coded as CL in the database of the pathology department between 2004 and 2019 were included in the study. Medical records were retrospectively reviewed to obtain the following data: age, sex, location, number of lesions, diameter, evolution time at diagnosis, suspected clinical diagnosis, tenderness, status of resection margins, development of recurrence, follow-up time, and association with HLRCC. RESULTS: 152 patients had CLs, 89 women and 63 men, mean age 56.26, SD 16.030 years. Subtypes were piloleiomyoma in 62 patients, angioleiomyoma in 80, and genital leiomyoma in 10. All of our 11 patients with multiple lesions corresponded to piloleiomyomas, and HLRCC was confirmed in 8 of them (73%). Patients with HLRCC were younger than patients with piloleiomyomas without HLRCC (34.88 vs. 56.17 years, p = 0.009). Vascular and genital leiomyomyomas were solitary and were not associated with HLRCC. CONCLUSION: In patients with multiple piloleiomyomas HLRCC must be ruled out as it is confirmed in a high proportion of cases. The probability of fumarate hydratase mutation is greater in multiple piloleiomyomas involving both the trunk and upper extremities in the same patient.

Sarcoidosis Induced by Atezolizumab Presenting With Xanthelasma Infiltration.

ABSTRACT: Sarcoidosis induced by anti-PD1 or anti-PDL1 agents such as atezolizumab has recently been reported. It has been suggested that the predilection of sarcoidosis to affect scars is due to the presence of antigens or foreign bodies that can serve as a stimulus for granuloma formation. However, to the best of our knowledge, sarcoidosis-specific skin lesions have not to date been reported involving xanthelasma. We report a patient who developed specific lesions of sarcoidosis infiltrating some xanthelasmata 6 months after starting treatment with atezolizumab. A 69-year-old woman was referred to the dermatology department for infiltration of xanthelasmata. The patient was being treated with atezolizumab for metastatic uterine carcinosarcoma. Cutaneous biopsy from an infiltrated xanthelasma and from still yellow, no infiltrated xanthelasma showed differing proportions of foamy histiocytes and sarcoid granulomas. On physical examination, erythemato-marronaceous papules clustered on both knees, and not previously detected by the patient, were observed. The biopsy showed sarcoid dermal granulomas with foreign bodies. A chest computerized tomography scan was consistent with intrathoracic involvement of sarcoidosis. Endobronchial ultrasound-guided transbronchial needle aspiration of a mediastinal lymphadenopathy showed epithelioid cell granulomas. Histopathologically, the foamy histiocytes of xanthelasma seem to be replaced by or evolve to epithelioid cells to form sarcoid granulomas. The possible pathogenic mechanism is discussed. Dermatologists and dermatopathologists should bear in mind that sarcoidosis can present as infiltration of pre-existing xanthelasmata.

Histopathological Features of Subcutaneous Sarcoidosis.

Only a few series of patients with systemic sarcoidosis and specific subcutaneous lesions have been reported. We reviewed our patients with systemic sarcoidosis with specific subcutaneous lesions to analyze their histopathological features and their relationship with clinical features of the systemic disease. Patients with systemic sarcoidosis with predominantly subcutaneous sarcoid granulomas diagnosed between 1980 and 2016 in Bellvitge University Hospital were enrolled. We also analyzed patients with clinically and histopathologically identical lesions in whom a diagnosis of systemic sarcoidosis could not be made during follow-up. Twenty-eight patients with systemic sarcoidosis presented specific subcutaneous lesions (23 women and 5 men, mean age 55.64 SD 12.26 years). Dermal involvement was observed in 10 cases, always discrete and limited to deep reticular dermis. The distribution of the granulomatous infiltrate was lobular in 7 cases and lobular and septal in 21. Fibrosis was observed in 21 cases. There were no significant differences in persistence of lesions or persistence of systemic disease activity when comparing patients with and without fibrosis. In conclusion, fibrosis is a frequent finding in subcutaneous sarcoidosis, and although it may be intense, it is not associated with pulmonary fibrosis or with >2 years of persistence of systemic sarcoidosis activity.

Primary cutaneous vs secondary cutaneous follicular lymphomas: A comparative study focused on BCL2, CD10, and t(14;18) expression.

BACKGROUND: Primary cutaneous follicular center-cell lymphoma (PCFCL) is one of the most common types of cutaneous B-cell lymphoma. Differences in immunohistochemical expression of BCL2 and CD10 antigens along with the presence of t(14:18) translocation in neoplastic cells have been postulated as relevant clues in differentiating PCFCL from cutaneous lesions secondary to a systemic follicular lymphoma (SCFL). The aim of this study is to evaluate the significance and usefulness of these parameters in a large series of patients. METHODS: Patients with PCFCL and SCFL diagnosed at three university hospitals in Barcelona, from 2000 to 2015 were reviewed. Clinical, histopathological, immunophenotypical, genetic, and outcome parameters were analyzed. RESULTS: Eighty-one cases (59 PCFCL and 22 SCFL) were included. There were no significant differences between PCFCL and SCFL cases regarding clinical presentation, site of involvement, or predominant type of skin lesions. Most patients in both groups showed positivity for BCL2 and CD10, but strong expression of BCL2 and CD10 was associated with SCFL cases. Although more frequent in SCFL, a small proportion of PCFCL cases also showed the t(14:18) on FISH analysis. CONCLUSION: The intensity of BCL2 expression was found to be the single most valuable clue in differentiating PCFCL from SCFL cases on histopathological grounds.

Specific Skin Lesions of Sarcoidosis Located at Venipuncture Points for Blood Sample Collection.

It has been suggested that the predilection of sarcoidosis to affect scars is due to the presence of antigens or foreign bodies that can serve as a stimulus for granuloma formation. Several patients with sarcoidosis-specific skin lesions in venous puncture sites have been reported. However, in these patients the pathogenesis of the cutaneous lesions is not clear because the presence of foreign bodies is not to be expected. Our objective was to describe 3 patients who developed specific lesions of sarcoidosis in areas of venipuncture and to discuss their possible pathogenesis. The database of the Sarcoid Clinic of Bellvitge Hospital (an 800-bed university referral center providing tertiary care to approximately 1 million people in Barcelona, Spain) was reviewed to detect those patients with specific cutaneous lesions of systemic sarcoidosis in areas of venipuncture. Three patients with biopsy-proven specific cutaneous lesions of systemic sarcoidosis in areas of venipuncture for blood collection were detected (3 women, mean age 56 years). In one case, the histopathological image shows the hypothetical path of a needle through the skin. In 2 cases, an amorphous birefringent material was detected under polarized light. This material was consistent with silicone. In patients who are developing sarcoidosis, the smallest amount of oil used as lubricant in the needle for sample blood collection may induce the formation of granulomas. In addition to exploring scars, it is advisable to explore the cubital folds to detect specific cutaneous lesions of sarcoidosis.

Cutaneous Neoplasms in Myotonic Dystrophy Type 1.

BACKGROUND: The most frequent skin features associated with myotonic dystrophy type 1 (DM1) are frontal alopecia and pilomatrixomas. Several reports suggest that the incidence of basal cell carcinoma is increased in DM1. However, two recently published studies examining this topic have contradictory results. OBJECTIVE: To retrospectively study the incidence of cutaneous tumours in patients with DM1. METHODS: The clinical features of 102 Caucasian patients diagnosed with DM1 at Bellvitge Hospital in Barcelona, Spain, were retrospectively analysed. Clinical charts of the patients were reviewed, and cutaneous tumours diagnosed in our hospital were recorded. A group of 103 Caucasian patients matched for age and sex were used as the control group. RESULTS: A total of 56 male and 46 female patients with DM1 were included in the study (mean age 49.07 years, SD 13.02). At least 1 basal cell carcinoma was diagnosed in 6 patients in the DM1 group versus 3 patients in the control group (p = 0.332). The mean age at diagnosis of the first basal cell carcinoma was 51 years compared with 66 years in the control group (p = 0.035). Five patients with DM1 presented pilomatrixomas versus none in the control group (p = 0.029). We did not detect any melanoma in our DM1 patients. CONCLUSION: Basal cell carcinomas appeared at a significantly younger age in our DM1 patients than in the general population, and this suggests that, at least in some patients, DM1 may predispose to the development of basal cell carcinomas.

Histopathological Features of Orofacial Granulomatosis.

Orofacial granulomatosis (OFG) is characterized by granulomatous inflammation in the orofacial region. Although several series have been reported, biopsy has not been performed in all cases and the histopathological features have not been extensively evaluated. Our purpose was to analyze the histopathological features of our patients with OFG. Twenty-two patients diagnosed with OFG at Bellvitge Hospital (Barcelona, Spain) from 1985 to 2010 were included in the study. All of our patients (14 men and 8 women; mean age 46.77 years, SD 13.61) presented with labial swelling, involving the upper lip in 13 cases and the lower lip in 9 at presentation. Fissured tongue was observed in 9 cases. Three patients suffered facial palsy. Granulomas were observed in 16 patients. All patients showed a perivascular, lymphohistiocytic inflammatory infiltrate with prominent plasma cells in 21 cases. In 5 cases, mast cells were easily observed. In 13 patients, an interstitial infiltrate was also present. All cases showed dilated lymphatic channels, and 19 edema of the lamina propria or the dermis. Perilymphatic granulomas were observed in 12 cases, intralymphatic granulomas in 2, and intralymphatic histiocytes in 2. In conclusion, loose epithelioid cells or lymphonodular granulomas were observed in 73% of our patients. Although none of our patients developed Crohn disease, OFG is histopathologically similar to cutaneous lesions of Crohn disease. The perilymphatic disposition of granulomas and the presence in some cases of intralymphatic histiocytes or intralymphatic granulomas may explain the dilatation of lymphatic vessels and the development of edema.

Melanoma incidence increases in the elderly of Catalonia but not in the younger population: effect of prevention or consequence of immigration?

All cases of MM diagnosed in 23 hospitals in Catalonia, from 2000 to 2007 were recorded and melanoma incidence calculated and adjusted for the European standard population via the direct method. The age standardised rate/100,000 inhabitants varied from 6.74 in 2000 to 8.64 in 2007 for all melanomas and from 4.79 to 5.80 for invasive MMs; the Breslow thickness was stable during the period. The increase in invasive melanoma incidence in the elderly was remarkable, the crude rate/100,000 inhabitants increasing from 11.04 (2000) to 15.49 (2007) in the 60-64 year population, while remaining more stable in the 30-34 year range, from 3.97 in 2000 to 4.55 in 2007, and with a tendency to decrease from 5.1 in 2000 to 2.5 in 2007 for the age range of 25-29 years. These lower age ranges are much more affected by immigration. Despite the large immigrant population (nearly one million immigrants arrived in Catalonia during the study period from countries with a low melanoma incidence), melanoma incidence in our region has risen considerably and this trend is likely to persist in the near future.

Merkel cell carcinoma: differences between sun-exposed and non-sun-exposed variants--a clinical analysis of 36 cases.

BACKGROUND: There are few studies focusing on the clinical characteristics of Merkel cell carcinoma (MCC). OBJECTIVE: To retrospectively analyze the clinical features of our patients and their relationship with sun exposure. METHODS: Thirty-six patients diagnosed with MCC (20 men and 16 women, mean age 72.08 years) were included in the study. RESULTS: 21 patients developed MCC in sun-exposed skin and 15 patients in non-sun-exposed areas. MCC was >2 cm in 19 cases. Six of the 7 patients who died as a result of MCC had non-sun-exposed tumors. Only tumor size >2 cm significantly influenced survival (p = 0.033). CONCLUSION: Sun-exposed lesions tended to be <2 cm in diameter and were more common in men, while non-sun-exposed tumors were larger, usually occurring in women and carrying a greater likelihood of death by MCC. Non-sun-exposed tumors usually present as fast-growing, multilobar nodular lesions with a smooth shiny surface.

Specific cutaneous involvement in Whipple disease.

Cutaneous lesions in Whipple disease (WD) are infrequent, and the histological findings are usually nonspecific. Specific cutaneous lesions have rarely been described and usually involve the subcutaneous fat. We report a patient diagnosed with WD, who developed multiple small subcutaneous nodules after antibiotic treatment was administered. In addition to septal panniculitis, the cutaneous biopsy showed a mild granulomatous dermal reaction with PAS-positive macrophages characteristic of WD. A positive polymerase chain reaction in the cutaneous sample confirmed the presence of Tropheryma whipplei in the skin. Dermatopathologists should be aware that not only subcutaneous lesions but also dermal lesions may exhibit specific findings of WD.

Dermatomyositis in a donor and receptor of allogenic hematopoietic stem cell transplantation: Auto- or alloimmune disease?

We present the case of a 63-year-old woman who developed dermatomyositis after hematopoietic stem cell transplantation. Anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibodies were positive and pulmonary involvement was severe and progressive. In addition, we also report that the patient's sister and donor also developed dermatomyositis. She had positive anti-PL7 antibodies and negative anti-MDA5 antibodies. The occurrence of autoimmune diseases after allogeneic hematopoietic stem cell transplantation is infrequent and difficult to interpret due to the reconstitution of the immune system and the multifactorial origin of most of these diseases. To our knowledge, this is the first described case of a hematopoietic progenitor transplant donor and recipient developing dermatomyositis. These findings make us wonder whether the dermatomyositis in this case is due to a shared genetic predisposition or to the donor's disease developing in the recipient.

PRRX1 silencing is required for metastatic outgrowth in melanoma and is an independent prognostic of reduced survival in patients.

Paired related homeobox 1 (PRRX1) is an inducer of epithelial-to-mesenchymal transition (EMT) in different types of cancer cells. We detected low PRRX1 expression in nevus but increased levels in primary human melanoma and cell lines carrying the BRAFV600E mutation. High expression of PRRX1 correlates with invasiveness and enrichment of genes belonging to the EMT programme. Conversely, we found that loss of PRRX1 in metastatic samples is an independent prognostic predictor of poor survival for melanoma patients. Here, we show that stable depletion of PRRX1 improves the growth of melanoma xenografts and increases the number of distant spontaneous metastases, compared to controls. We provide evidence that loss of PRRX1 counteracts the EMT phenotype, impairing the expression of other EMT-related transcription factors, causing dysregulation of the ERK and signal transducer and activator of transcription 3 (STAT3) signaling pathways, and abrogating the invasive and migratory properties of melanoma cells while triggering the up-regulation of proliferative/melanocytic genes and the expression of the neural-crest-like markers nerve growth factor receptor (NGFR; also known as neurotrophin receptor p75NTR) and neural cell adhesion molecule L1 (L1CAM). Overall, our results indicate that loss of PRRX1 triggers a switch in the invasive programme, and cells de-differentiate towards a neural crest stem cell (NCSC)-like phenotype that accounts for the metastatic aggressiveness.

Cutaneous metastasis from lung cancer: retrospective analysis of 30 patients.

Lung carcinoma is one of the most frequent sources of skin metastases in male patients. Our objective was to analyse the clinical and pathological features of 30 patients with skin metastases from lung carcinoma. Cutaneous biopsies codified as 'skin metastasis from lung carcinoma' during 1988-2009 at Bellvitge Hospital (Barcelona, Spain) were reviewed. The histological types of 30 lung carcinomas (29 men, 1 woman) were squamous cell carcinoma (10 cases), undifferentiated carcinoma (7), adenocarcinoma (6), small cell carcinoma (5) and large cell carcinoma (2). The most frequent clinical presentation was as a solitary nodule (16 cases), and the most frequent site was the head (13 cases). Cutaneous metastases were present at the time of diagnosis of the lung primary tumour in 66% of cases. Skin biopsy might be helpful to establish the histological type of tumour, and thus help with therapeutic decision-making. Cutaneous metastases from lung cancer remain a poor prognostic feature.

[Granulomatous mastitis associated with erythema nodosum: A case series of 42 patients]. / Mastitis granulomatosa asociada a eritema nudoso: estudio de 42 casos.

BACKGROUND: Granulomatous mastitis (GM) is defined by the formation of granulomatous inflammation in breast tissue. Erythema nodosum (EN) is a reactive inflammatory panniculitis characterized by erythematous subcutaneous nodules in the lower limbs. The association of GM with EN has been rarely reported. Our aim was to retrospectively review our series of patients with GM to better characterize their features and their association with EN. METHODS: Cases histologically diagnosed as granulomatous inflammation in breast tissue between 1995 and 2020 were retrospectively reviewed. RESULTS: Forty-two women were diagnosed with GM. The average age at diagnosis was 41.619years, and 59.5% were of South-American ethnicity. EN was associated with GM in 11.9% of the patients. Patients with EN were diagnosed earlier than isolated GM (0.4months vs 6.81months; P<.05). Ulceration in the GM was more prevalent in patients with associated EN (60% vs 14.7%; P<.05). CONCLUSION: EN in patients with GM may reduce the evolution time and may help to diagnose this rare condition that mimics breast carcinoma.

Granuloma Annulare: a Case-control Study of Possible Associated Diseases.

Introduction: Granuloma annulare (GA) has been reported as associated with multiple diseases, mainly diabetes mellitus (DM), thyroid diseases, and dyslipidemia. However, the high prevalence of some of these illnesses makes it difficult to assess whether the association is real or fortuitous. Objectives: Our objective was to analyze the clinical features of GA patients and the possible associations. Methods: This is a retrospective observational study of 225 patients with biopsy-proven GA diagnosed between 2009 and 2019 in a referral university hospital in Barcelona, Spain. Clinical charts were reviewed to obtain clinical data. As a control group we used a random list of 225 patients diagnosed in the hospital traumatology department in the same period, matched by age and sex. Results: Diabetes was diagnosed in 40 GA patients (18%) (34 in the control group, 15%) and hypothyroidism in 33 (15%) (22 in the control group 9.8%); the differences were not significant. We also did not detect any association with uveitis, sarcoidosis, necrobiosis lipoidica, Sweet syndrome, HIV infection, hepatitis B, or hematological malignancies. We only detected a possible association with hepatitis C (6 GA patients, 2.7%, versus 0 controls, P = 0.03), and hypercholesterolemia (108 GA patients, 48%, versus 79 controls, 35%, P = 0.007). Conclusions: The possible pathogenic explanations for the association with hepatitis C and hypercholesterolemia seem unlikely. We consider that the association of GA with other diseases, including hypercholesterolemia and hepatitis C, is doubtful and that it there is no justification rule out possible associated diseases in patients with GA.

Oncogenic properties via MAPK signaling of the SOX5-RAF1 fusion gene identified in a wild-type NRAS/BRAF giant congenital nevus.

We recently reported an RAF rearrangement without NRAS or BRAF mutations in lesions from Giant Congenital Melanocytic Nevi (CMN). The new gene fusion involves the 5'-end of the promoter-containing N terminus of the SOX5 gene fused to exons 7-16 of the 3'-end of RAF1 gene leading to a SOX5-RAF1 fusion transcript which loses the auto-inhibitory CR1 domain but retains the complete in-frame coding sequence for the C-Terminal kinase domain of the RAF1. Stable expression of SOX5-RAF1 fusion induced growth factor-independent cell growth in murine hematopoietic Ba/F3 cells and melan-a immortalized melanocytes. Besides, it led to the transformation of both Ba/F3 and NIH 3T3 cells as revealed by colony formation assays. Furthermore, its expression results in MAPK activation assessed by increased levels of p-ERK protein in the cytosol of transduced cells. Treatment with Sorafenib and UO126 inhibited proliferation of Ba/F3-SOX5-RAF1 cells in the absence of IL3 but not the PLX 4720, a specific inhibitor of BRAF. Moreover, the tumorigenic and metastatic capacities of SOX5-RAF1 were assessed in vivo. These results indicate that SOX5-RAF1, a driver event for CMN development, has oncogenic capacity. Thus, sequencing of CMN transcriptomes may lead to the identification of this druggable fusion and interfere with the progression toward melanoma.