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Granulomatous Diseases
Published in Ayşe Serap Karadağ, Lawrence Charles Parish, Jordan V. Wang, Roxburgh's Common Skin Diseases, 2022
Albert Alhatem, Robert A. Schwartz, Muriel W. Lambert, W. Clark Lambert
Overview: Xanthogranuloma (XG) is a moderately uncommon, benign, proliferative histiocytic disorder, which originates from dermal factor XIIIa positive dendrocytes. It is the most common of the non-Langerhans cell histiocytosis, occurring predominantly in young children.
Comparative Anatomy, Physiology, and Biochemistry of Mammalian Skin
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
Two types of Langerhans’ cells have been observed in normal human skin. One is dendritic with a moderately electron dense cytoplasm and numerous Langerhans’ granules but relatively few lysosomes and mitochondria. The second one appears less dendritic, occurs more frequently in the basal layers, has an electron-dense cytoplasm, fewer granules, and numerous mitochondria, some of which appear swollen, vacuolated, and without cristae.146,153
Describe how antigen is presented to T lymphocytes
Published in Nathaniel Knox Cartwright, Petros Carvounis, Short Answer Questions for the MRCOphth Part 1, 2018
Nathaniel Knox Cartwright, Petros Carvounis
Antigen-presenting cells include the following: macrophages are large white blood cells that ingest antigens and other foreign substances which are then destroyed chemically or enzymatically after antigen presentationdendritic cells are the principal APCs of the primary immune response, although dendritic cells themselves do not actually mediate specific immune responses. Their major function is to obtain antigen in tissues before migrating to lymphoid organs where they activate T cells. Langerhans cells are dendritic cells specific to skin.
Iris Juvenile Xanthogranuloma Presenting with Hypopyon
Published in Ocular Immunology and Inflammation, 2022
Mine Esen Baris, Mukaddes Damla Ciftci, Melis Palamar, Suzan Guven Yilmaz
A 45-day-old infant was referred to our clinic for unilateral hypopyon. The mother indicated noticing a whitish color change in the left eye multiple times that resolved rapidly. However, at the time of consultation, the whiteness was more intense and was retained for almost 2 weeks. The baby was examined under general anesthesia and found to have hypopyon that gave a level of about 2 mm in the left eye. No pathology was observed in the visible areas of the iris. Intraocular pressure (IOP) was 13 mmHg (Tono-Pen®, TP; Reichert, New York, USA) and the fundus examination was completely normal. Anterior and posterior segment examinations of the right eye were normal and IOP was 12 mmHg. B-scan ultrasound examinations of both eyes were within normal limits. Cranial and orbital MRI scans were reported to be normal as well. Complete blood count, along with the erythrocyte sedimentation rate and C-reactive protein levels, was within normal limits. Langerhans cell histiocytosis and granulomatous infections (tuberculosis and syphilis) were investigated. Syphilis was excluded by serological tests and interferon gamma release assay (IGRA) was applied for exclusion of tuberculosis. Examinations of the infant by the pediatrician and the blood tests along with cranial and orbital MRI revealed no pathology; therefore, Langerhans cell histiocytosis was also excluded.
The global challenge of treating disseminated LCH
Published in Pediatric Hematology and Oncology, 2020
In this article, Tantawy et al. present the clinicopathologic features of Langerhans cell histiocytosis (LCH) and treatment outcomes in a retrospective cohort of 37 Egyptian children.1 Unlike previous reports from North America and Europe, a majority of the patients had high-risk disease (64.8% of total cohort). However, similar to the data from the international LCH registry of multisystem LCH, the authors reported a reactivation rate of 29.7% with the highest rate of reactivation reported in the multisystem risk organ (MS-RO+) group (7/11 reactivations, ie 64% reactivation rate). Seven children had progressive disease, all of whom at MS-RO + at baseline. In this Egyptian series, multisystem (MS) versus single-system (SS) disease did not seem to have a statistically significant impact on the 5-year event-free or overall survival, though patients with MS disease did worse than their counterparts. More importantly, risk-organ involvement presaged a higher rate of progressive disease, reactivations and eventually death, irrespective of response at 6 weeks. Thus, this article not only highlights the urgent need to optimize upfront therapy for children with MS disease but also underscores the acute need for more effective salvage therapy for children with MS-RO + LCH.
A case of multisystem Langerhans cell histiocytosis presenting as central diabetes insipidus
Published in Journal of Community Hospital Internal Medicine Perspectives, 2019
P. Daniel Nicholas, Ian Garrahy
The label Langerhans cell histiocytosis (LCH) derived from histologic studies of biopsied lesions. It was noted that the malignant histiocytes contain Birbeck granules and the protein langerin (CD207), both associated with Langerhans cells (LC), and it was postulated that the epidermal LC underwent a malignant transformation in LCH. However, a subsequent cytologic study illustrated that the dendritic cells that form LCH lesions are actually precursors from the bone marrow that travel to lesion sites and differentiate into langerin+ cells, a theory termed the ‘Misguided Myeloid Dendritic Cell Precursor’ model [1]. Animal studies confirmed the identity of LCH as a myeloid neoplasia by demonstrating that inducing a point mutation implicated in the disease’s pathogenesis, BRAF-V600E, in bone marrow dendritic cell progenitors resulted in a phenotype mimicking high-risk LCH in humans, while inducing the same mutation in differentiated dendritic cells resulted in a low-risk LCH phenotype [6].