Malignant tumors result from the accumulation of genetic alterations in oncogenes and tumor suppressor genes. Much less is known about the genetic changes in benign tumors. Seborrheic keratoses (SK) are very frequent benign human epidermal tumors without malignant potential. We performed a comprehensive mutational screen of genes in the FGFR3-RAS-MAPK and phosphoinositide 3-kinase (PI3K)-AKT pathways from 175 SK, including multiple lesions from each patient. SK commonly harbored multiple bona fide oncogenic mutations in FGFR3, PIK3CA, KRAS, HRAS, EGFR, and AKT1 oncogenes but not in tumor suppressor genes TSC1 and PTEN. Despite the occurrence of oncogenic mutations and the evidence for downstream ERK/MAPK and PI3K pathway signaling, we did not find induction of senescence or a DNA damage response. Array comparative genomic hybridization (aCGH) analysis revealed that SK are genetically stable. The pattern of oncogenic mutations and X chromosome inactivation departs significantly from randomness and indicates that spatially independent lesions from a given patient share a clonal relationship. Our findings show that multiple oncogenic mutations in the major signaling pathways involved in cancer are not sufficient to drive malignant tumor progression. Furthermore, our data provide clues on the origin and spread of oncogenic mutations in tissues, suggesting that apparently independent (multicentric) adult benign tumors may have a clonal origin.

Background Activating RAS mutations in the germline cause rare developmental disorders such as Costello syndrome. Somatic RAS mutations are found in approximately 30% of human cancers. Keratinocytic epidermal nevi (KEN) represent benign congenital skin lesions arranged along Blaschko's lines. A subgroup of KEN is caused by hotspot oncogenic FGFR3 and PIK3CA mutations in mosaicism, but the majority lack these mutations. Methods This study screened 72 KEN for activating mutations in RAS genes and other oncogenes. Results Activating RAS mutations were identified in 28/72 (39%) of KEN. HRAS was the most commonly affected oncogene (86%), with the HRAS p.G13R substitution representing a new hotspot mutation. Conclusion These results indicate that activating RAS somatic mutations leading to mosaicism result in benign KEN of the skin. Given the prevalence of KEN, mosaic HRAS mutations appear to be more common in patients than germline ones. These findings identify KEN as a mosaic RASopathy and lend further support to the notion that genetic mosaicism is an important contributor to disease.

Leishmania infection seems to be an important aetiological factor in cutaneous granulomatous lesions showing nondiagnostic features in endemic areas. In such areas, Leishmania-specific PCR amplification and/or immunohistochemical studies may be useful diagnostic tools. These techniques may be specifically indicated in the evaluation of patients showing nonspecific granulomatous inflammatory infiltrates of unknown aetiology lacking the histopathological evidence of parasites.

We describe a 41-year-old human immunodeficiency virus-infected woman with a previous history of intravenous drug abuse, who developed multiple linear nodules following the superficial veins on both arms. Histopathological examination disclosed a dermal histiocytic inflammatory reaction with sarcoid-like granuloma formation occasionally showing an intracytoplasmic refractile material in the histiocytic cells. Nodular lesions developed progressively after starting on highly active antiretroviral therapy (HAART) which increased her CD4 cell count and suppressed her viral load. The appearance of latent inflammatory or autoimmune disease following HAART is a well-recognized phenomenon. We consider that this peculiar 'progressive supravenous granulomatous nodular eruption' should be included within the spectrum of the so-called immune reconstitution inflammatory syndrome.

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images in clinical medicineT h e ne w e ngl a nd jou r na l o f m e dic i ne n engl j med 360;22 nejm.org may 28, 2009 e28 A 69-year-old woman with complete atrioventricular block was admitted for implantation of a pacemaker. Her medical history included multiple sclerosis with tetraparesis. She had been taking acenocoumarol for the previous 10 years for the treatment of deep venous thrombosis. Twenty-four hours after acenocoumarol was withdrawn before pacemaker implantation, intense lingual pain developed. On physical examination, a well-circumscribed, triangular necrotic area was detected on the tip of the tongue (Panel A). Surgical excision was performed. Histopathological analysis revealed ischemic necrosis and intraluminal thrombi without vasculitis (Panel B, arrow). The total peripheral-blood platelet count was 700,000 per cubic millimeter, and the diagnosis of essential thrombocytosis was confirmed on bone marrow biopsy and detection of the JAK2 V617F mutation. The patient's previous platelet count was unknown. Therapy with acenocoumarol and hydroxyurea was initiated, and the patient had a full recovery. The tongue is a rare location of ischemic necrosis, even in patients with essential thrombocytosis, because of the excellent blood supply and collateral circulation.

There are limited reports on the ultrastructure of syphilis skin lesions. The aim of this study has been to perform an electron microscopic investigation of the morphology and the tissue distribution of treponemes in primary and secondary cutaneous lesions. Three cases of primary syphilitic chancre and one case of secondary syphilis were included. Prominent epidermal abnormalities in the primary chancre and a perivascular inflammatory infiltrate in the secondary lesion were found by light microscopy. Ultrastructurally, spirochetes were located mainly in the blood vessel walls and dermal tissue of the chancre lesions. In the secondary syphilis case, spirochetes were more abundant between epidermal keratinocytes. Most of them adjusted to the intercellular spaces. Occasionally, the electron microscopy images were highly suggestive of an intracellular location. Both the ultrastructural and immunohistochemical examination of the primary and secondary syphilis lesions showed a paradoxical distribution of the causative microorganisms compared to the light microscopic changes. In addition, the ultrastructural findings strongly suggest that Treponema pallidum subspecies pallidum invades tissues, not only through an intercellular, but also through a transcellular pathway.

Imiquimod is a class of non-nucleoside imidazoquinolinamines which promotes local cytokine release from antigen-presenting cells inducing a T-h1 dominant cell-mediated response against virus-infected cells. Topical imiquimod 5 per cent cream, applied for four to 16 weeks, may offer some benefit in the management of recurrent nasal papillomata in human immunodeficiency virus positive patients. Such treatment may be preferable to surgery or destructive therapeutic options when patients are unwilling or are poor surgical candidates, and also avoids potential surgical sequelae such as scar formation and stenosis.