No abstract

Poroid hidradenoma is a benign soft-tissue neoplasm with eccrine differentiation. It is the newest addition to a group of neoplasms known as poromas. Although it becomes malignant in less than 1% of cases, its histologic characteristics may resemble those of malignant neoplasms; thus it is easily misdiagnosed. Twenty-one percent of poroid hidradenomas occur in the extremities. The histologic and clinical features of this tumor are presented here, along with a case report.

Study design: A case report of self-injurious behavior in four children and adolescents with spinal cord injuries (SCI). Objectives: To report a relatively unusual complication of pediatric-onset SCI, focusing on the potential role that dysesthesia may play in self-injurious behavior. Setting: A Spinal Cord Injury Program in a Children's Hospital in Chicago that serves children from midwestern and south-central United States of America. Method: Case reports and literature review. Results: Case reports are presented of four children or adolescents with SCI who exhibited self-injurious behavior. Two of the subjects had symptoms consistent with dysesthesia. The self-injurious behavior in these two subjects and a very young child responded to treatment with anticonvulsants. The self-injurious behavior in the fourth patient was probably the result of poor technique of using his mouth to move his hands, which responded to conservative management including education, occupational therapy and gloves. Conclusion: Self-injurious behavior is a relatively unusual complication of pediatric onset SCI, and may be a manifestation of dysesthesia and be responsive to treatment with anticonvulsants.

Histone H3 lysine 79 (H3K79) methylation is enriched on actively transcribed genes, and its misregulation is a hallmark of leukemia. Methylation of H3K79, which resides on the structured disk face of the nucleosome, is mediated by the Dot1L methyltransferase.Dot1L activity is part of a trans-histone crosstalk pathway, requiring prior histone H2B ubiquitylation of lysine 120 (H2BK120ub) for optimal activity. However, the molecular details describing both how Dot1L binds to the nucleosome and why Dot1L is activated by H2BK120 ubiquitylation are unknown. Here we present the cryo-EM structure of Dot1L bound to a nucleosome reconstituted with a site-specifically ubiquitylated H2BK120. The structure reveals that Dot1L engages the nucleosome acidic patch using an arginine anchor and occupies a conformation poised for methylation. Ubiquitin directly interacts with Dot1L and is positioned as a clamp on the nucleosome interacting region of Dot1L. Using our structure, we identify point mutations that disrupt the nucleosome-specific and ubiquitin-dependent activities of Dot1L. This study establishes a path to better understand Dot1L function in normal and leukemia cells.