Pablo Uribe

BRAF mutation: a frequent event in benign, atypical, and malignant melanocytic lesions of the skin.

BRAF mutations have recently been detected with a high frequency (66%) in cutaneous melanoma. All those mutations are activating, with a single substitution (T1796A) at codon 599 (V599E) accounting for over 90%. To investigate the stage in which those mutations occur in the currently proposed sequential malignant transformation of melanocytes, 22 benign melanocytic nevi, 23 melanocytic atypical nevi, and 25 primary cutaneous melanoma from 63 different patients were examined for BRAF mutations using DNA extracted from microdissected formalin-fixed and paraffin-embedded tissues, and a two-round PCR-RFLP–based strategy. A subset of samples was sequenced for mutation confirmation. Sixteen benign (73%) and eleven atypical (52%) melanocytic nevi, and thirteen melanoma (56%) demonstrated BRAF mutations at codon 599, and no statistically significant differences were detected among all three types of lesions. No mutations were demonstrated in microdissected epidermal keratinocytes adjacent to melanocytic lesions having BRAF mutations. No correlation was detected between BRAF mutational status and age, sun exposure, and Clarks level in malignant melanoma. However, comparing only atypical nevi and melanoma lesions the frequency of BRAF mutation is significantly greater in male (78%) than female (35%) patients (P = 0.0194). The previously described T1796A point mutation was detected in 17 of 18 mutated samples, and a novel mutation consisting of a substitution of valine for lysine (GT1795-96AA) was detected in one melanoma case. Our findings of a high frequency of BRAF mutations at codon 599 in benign melanocytic lesions of the skin indicate that this mutation is not sufficient by itself for malignant transformation.

Epidermal growth factor receptor (EGFR) and squamous cell carcinoma of the skin: Molecular bases for EGFR-targeted therapy

Cutaneous squamous cell carcinoma (SCC) ranks second in the frequency of all skin tumors. Its incidence has risen significantly due to an increased sun exposure and the number of immunocompromised patients. It has a well-defined progression with known precursor lesions called actinic keratosis. The degree of cellular differentiation, tumor thickness, location, and other features has prognostic value. It has a better prognosis than mucosal SCC of the head and neck, also called head and neck squamous cell carcinoma (HNSCC). Ultraviolet light plays a fundamental role as an initiator and promoter of carcinogenesis of SCC, allowing the accumulation of genetic alterations that allows a selective growth advantage. The TP53 (p53) gene often mutates and Ras is frequently activated, but with low frequency of mutations. Normally, the extracellular signals determine whether the cells move from a quiescent state into an active proliferative state. In tumor cells an increase in the production of growth factors and its receptors can be often seen that gives rise to such an autocrine circuit facilitating cellular division. Recently, frequent mutations in the epidermal growth factor receptor (EGFR) have been detected in lung cancer, mainly deletions in exon 19 and L858R mutation in exon 21. These are located at the EGFR tyrosine kinase domain (TK). EGFR TK mutations produce activation of the signaling pathways downstream and preferentially activated antiapoptotic pathways (PI3K/AKT, JAK-STAT and ERK/MAPK). These mutations are correlated with the clinical response of patients to tyrosine kinase inhibitors (gefinitib and erlotinib), because the tumor cells are addicted to the constant activation of specific signaling pathways. Glioblastoma shows another EGFR mutation (EGFRvIII), corresponding to a deletion of the extracellular domain, and it is present in 24-67% of these tumors. This variant has been found in 42% of HNSCC, related to the poor response to monoclonal antibody cetuximab. Many observations show that there are abnormalities in the expression of epidermal growth factor receptor (EGFR) and/or its ligands in HNSCC with frequent activation of multiple pathways downstream EGFR, and unrelated to RAS mutation. This suggests the possibility of activation by mutation or overexpression of a component of the pathway located upstream-Ras. While in other tumors, especially lung cancer and glioblastoma, the EGFR mutations are frequent genetic events, it is unknown whether EGFR is mutated or amplified in SCC of the skin and what would be its pathogenic role in this malignancy and its precursors.

High-risk cutaneous squamous cell carcinoma and the emerging role of sentinel lymph node biopsy: A literature review

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer in the world. A minority of patients will be given a diagnosis of a high-risk cSCC (HRcSCC) and a proportion of these will have a poor outcome. HRcSCC is characterized by an increase in aggressiveness manifested as locoregional recurrence, and occasionally death. The utility of sentinel lymph node biopsy in this group of patients is unclear without high-level evidence or clear-cut recommendations. If clinicians accept a cutoff threshold of 10% risk of harboring occult nodal metastasis, then a selected group of patients with HRcSCC may benefit from sentinel lymph node biopsy. We performed a review of the currently available evidence, in the form of systematic reviews, meta-analysis, trials, and case series and analyzed the features that define a HRcSCC and the feasibility of performing sentinel lymph node biopsy in this group of patients.

Comparative analysis of loss of heterozygosity and microsatellite instability in adult and pediatric melanoma

Although 0.3% of melanomas occur in children, the incidence has risen in past decades. In adult melanoma, some chromosomal regions in 1p, 6q, 9p, 10q, and 11q are frequently deleted. Microsatellite instability (MSI), which reflects impaired DNA repair, has been found at low levels in adult melanoma and melanocytic nevi. To investigate the molecular changes in pediatric melanoma, a screening for loss of heterozygosity and microsatellite instability was performed and compared with changes found in adult melanoma. Formalin-fixed, paraffin-embedded tissues from 10 adult melanomas, 9 melanocytic nevi, and 8 pediatric melanomas were microdissected and the DNA was extracted. Loss of heterozygosity and microsatellite instability were evaluated using 13 microsatellite repeat polymorphisms located in 1p36, 1q32, 2p12, 2p22-25, 2q33-37, 9p21, 10q23.3, 11q23, 13q14, 17p13, and 17q21. The overall frequency of loss of heterozygosity was 0.09 for nevi, 0.30 for adult melanoma, and 0.43 for pediatric melanoma (nevi vs. adult melanoma, P = 0.0082; nevi vs. pediatric melanoma, P = 0.0092). Pediatric melanoma has more loss of heterozygosity (44%) in 11q23 than adult melanoma (7%, P = 0.046). The microsatellite instability overall frequency was greater in pediatric melanoma (0.24) than nevi (0.05, P = 0.0031) and adult melanoma (0.09, P = 0.0195). Our findings suggest that pediatric melanoma has a different abnormal pattern than adult melanoma. Pediatric melanoma has more microsatellite instability than adult melanoma. 11q23 could contain genes related to the early age onset of melanoma. The high frequency of microsatellite instability is coincidental with the finding of higher levels of microsatellite instability in pediatric brain tumors and could play a role in the pathogenesis of pediatric melanoma.

Acneiform eruptions: a common cutaneous toxicity of the MEK inhibitor trametinib.

The MEK inhibitor trametinib is currently undergoing clinical trials as the treatment of metastatic melanoma both alone and in combination with the BRAF inhibitor dabrafenib. One of the most frequent side‐effects associated with its use as a single agent is the development of acneiform eruptions. These eruptions seem to be reduced when dosed in combination with dabrafenib.

Allelotyping, microsatellite instability, and braf mutation analyses in common and atypical melanocytic nevi and primary cutaneous melanomas

Loss of heterozygosity (LOH) in several chromosomal regions is found in melanoma, and it has been partially studied in nevi. BRAF mutations are found in melanoma and nevi and in colorectal cancer are linked to mismatch repair deficiency. We studied early genetic events involved in melanomagenesis through analysis of allelic loss, microsatellite instability (MSI), and BRAF mutations.DNA extracted from microdissected cells of 22 common nevi, 23 atypical nevi, and 25 primary cutaneous melanomas were examined for LOH and MSI by polymerase chain reaction-based analysis of 24 microsatellite markers and BRAF mutation. Allelic loss index was higher in atypical nevi (0.20) and melanomas (0.27) than common nevi (0.07). LOH was frequent at 9p21, 17q21, 6q23, and 5q35 in melanoma. LOH at any of this loci occurred in 27% of common nevi, 57% of atypical nevi, and 68% of melanomas. BRAF mutations were not related to MSI presence and MSI index was not related with BRAF mutational status. Similar genetic alterations in atypical nevi and melanomas support the concept of atypical nevus as melanoma precursor. Novel deletion loci at 5q35 and 17q21 (BRCA1) in atypical nevi and melanomas were identified. Mismatch repair deficiency is not a crucial event for BRAF mutation in melanocytic tumors.

Acneiform eruption in a patient with metastatic melanoma after ceasing combination dabrafenib/trametinib therapy.

BRAF inhibitors (BRAFi) and MEK inhibitors (MEKi) increase survival in BRAF mutant metastatic melanoma patients; however, they induce a well-known spectrum of cutaneous side effects during treatment. Whereas the BRAFi dabrafenib induces cutaneous squamous cell carcinomas and verrucal keratosis, the MEKi trametinib frequently induces acneiform eruptions that are reversible after drug discontinuation. Furthermore, when dabrafenib and trametinib are used in combination, there are fewer cutaneous toxicities. We report a patient with BRAF mutant metastatic melanoma treated with the BRAFi/MEKi combination therapy who developed an acneiform eruption after treatment discontinuation rather than during active therapy. Moreover, the eruption resolved when the combination treatment was reintroduced and recurred after increasing the dose of trametinib. The eruption may be explained by the longer half-life of trametinib (4.5 days) compared with dabrafenib (5.2 h). This is the first case reported with this particular side effect induced after stopping the treatment and could become more frequent as the BRAFi/MEKi combination of drugs is more frequently prescribed.

Melanocytes and Keratinocytes Transfer Using Sandpaper Technique Combined with Dermabrasion for Stable Vitiligo

BACKGROUND Surgery is currently the most successful approach for difficult cases of vitiligo. The efficacy of epidermal surface removal (dermabrasion) is near 50%, and the efficacy of grafts is 70%. OBJECTIVE To evaluate the efficacy and safety of a combined approach using dermabrasion and grafting for unresponsive vitiligo. PATIENTS AND METHODS Eleven patients with stable vitiligo each underwent two different procedures on different body areas: transfer of melanocytes and epidermal cells obtained using the “sandpaper method” combined with dermabrasion of the receptor area or simple dermabrasion. Micropunch testing was used to evaluate the activity of vitiligo. Only patients without activity were treated. Subjects were followed for 3 months, and digital pictures were analyzed to estimate the percentage of repigmentation. RESULTS Transfer delivered visible results in the first month, and dermabrasion showed results in the second month. The quality of pigmentation was superior with the transfer technique, especially in the short term, although at the end of treatment, both techniques showed similar results. CONCLUSIONS Transfer of melanocytes and keratinocytes with the sandpaper method is feasible, safe, and effective as treatment for stable vitiligo, although simple dermabrasion is as effective in the long term. The authors have indicated no significant interest with commercial supporters.

In Vivo Reflectance Confocal Microscopy for the Diagnosis of Melanoma and Melanotic Macules of the Lip

Importance Benign melanotic macules (MAC) are the most frequent cause of lip pigmentation and sometimes difficult to differentiate from lip melanoma (MEL). Objectives To report in vivo reflectance confocal microscopy (RCM) features of normal lips of different phototypes and to identify features that assist in distinguishing MEL from MAC using dermoscopy and RCM. Design, Setting, and Participants For this retrospective observational study, 2 groups of patients from 2 tertiary referral centers for melanoma (Sydney Melanoma Diagnostic Centre and Melanoma Institute Australia) were recruited between June 2007 and January 2015. Group 1 included patients with normal lips and different phototypes, and Group 2 consisted of patients with MAC and MEL; RCM and dermoscopy were used for lips analysis. Main Outcomes and Measures Overall, 92 RCM features were correlated with clinical history, dermoscopic images, and histopathology in all patients with MEL and 5 patients with MAC. Results Images from the vermillion and/or mucosal part of the lip were recorded from 10 patients with clinically normal lips (mean [SD] age, 34.5 [6.1] years), 16 patients with MAC (mean [SD] age, 49.6 [17.9] years), and 5 patients with 6 cases of MEL (1 patient had a recurrent lesion; mean [SD] age, 56.2 [15.5] years). In normal lips, the draped pattern—a previously described MAC RCM feature—was identified in all cases. In MEL, the following findings were frequent and significantly different from MAC: epidermal disarray; pagetoid infiltration of dendritic and/or round cells; a nonspecific architectural pattern at the dermoepidermal junction (DEJ); nonhomogenously distributed papillae; continuous (lentiginous) proliferation of cells with marked atypia at the DEJ, especially in interpapillary spaces; a higher number of dendritic cells (especially roundish); and atypical round cells at the DEJ. The cellular body area of dendritic cells was about the double in MEL compared with MAC. An RCM lip algorithm was developed that provided 100% sensitivity and 88% specificity for the diagnosis of MEL of the vermillion and mucosal part of the lip. With dermoscopy, MAC were correctly classified as benign in 13 of 16 cases (81%) and MEL were classified as equivocal or malignant in 5 of 6 cases (83%). Conclusions and Relevance Reflectance confocal microscopy can assist in the differential diagnosis of lip MEL and MAC. An RCM Lip Score that we developed based on study results is proposed and needs to be validated on an independent data set.

Diffuse melanosis cutis in the setting of BRAF(V600E) mutant melanoma and treatment with targeted therapies.

Diffuse melanosis cutis (DMC) is a rare presentation of metastatic melanoma associated with a particularly guarded prognosis. We report a case of a 35‐year‐old man with BRAFV600E metastatic melanoma treated with dabrafenib (as well as ipilimumab and whole brain radiotherapy), who is alive, 25 months after the onset of his DMC. This is significantly longer than the reported mean survival of 4 months, highlighting the importance of BRAF mutation testing and the promising survival advantage of using targeted therapies compared with conventional chemotherapeutic regimens.