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Skin
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Zbigniew W. Wojcinski, Lydia Andrews-Jones, Daher Ibrahim Aibo, Rie Kikkawa, Robert Dunstan
The subcutis (hypodermis) contains abundant fat and loose connective tissue (collagen and elastic fibers) that connect the dermis to the underlying fascia, skeletal muscle, or bone. Fat cells may be arranged in small clusters or large masses (i.e., panniculus adiposus). The prominence of the subcutis varies by anatomic location and nutritional status. Adipose tissue is especially prominent in the footpads where it functions as a “shock absorber” and as an insulating layer (Lafontan 2012). The information and understanding on the role of adipocytes in the subcutis has been expanding during the last decade and now includes regulation of metabolism and energy homeostasis, as well as roles in angiogenesis and immune function (Miner 2004; Lafontan 2012). These cells secrete lipoprotein lipase that hydrolyzes triglycerides into very low-density lipoproteins and chylomicrons, or complement-related proteins including adipsin (or complement factor D). Adipocyte-derived hormones can have proinflammatory (IL-6, tumor necrosis factor alpha [TNF-α], plasminogen activator inhibitor-1, angiotensinogen, resistin, C-reactive protein) or anti-inflammatory (adiponectin and nitric oxide) activities (Miner 2004; Lau et al. 2005).
Case 3.4
Published in Monica Fawzy, Plastic Surgery Vivas for the FRCS(Plast), 2023
The skin is composed of two layers, the epidermis and dermis which rest on a panniculus adiposus:The epidermis is composed of four or five layers of stratified squamous epithelium that is of ectodermal origin but colonized by Melanocytes, Merkel cells-both of neural crest origin, and Langerhans cells-derived from the mesoderm.The layers, from deep to superficial, are Stratum: basale,spinosum,granulosum,lucidum – only present in glabrous skin, andcorneum.The dermis accounts for 95% of the skin thickness and is derived primarily from mesoderm. It is formed by the papillary and reticular dermal layers separated by a neurovascular plexus.The papillary dermis is superficial and contains more fibroblasts and finer collagen fibres.The reticular dermis is deeper and contains fewer fibroblasts with thicker collagen fibres.
Clinical guide to eosinophilic fasciitis: straddling dermatology and rheumatology
Published in Expert Review of Clinical Immunology, 2022
An autoimmune mechanism is presumed to be involved in the pathophysiology of EF, initiated by diverse triggers. The relation to strenuous physical exercise, originally described by Shulman, has been de-emphasized in recent works [1,2]. Several possible etiologies came into attention such as drug toxicity (antituberculous medications, phenytoin, simvastatin, atorvastatin, infliximab, pembrolizumab) [1], infections [3], radiation therapy, insect bites, and malignant neoplasia (the EF behaving as a paraneoplastic syndrome) [4]. A holistic concept [5] has been proposed in describing the set of disorders characterized by chronic inflammation and fibrosis of the subcutaneous septa and muscular fascia, under the term ‘fasciitis-panniculitis syndrome’ (FPS). The authors reported on data of 32 consecutive patients with EF and related syndrome cared for during 10 years. There were 14 cases of idiopathic FPS, i.e. EF, FPS secondary to vascular in 6, initiated by infections in 6, paraneoplastic in 3 cases. One case each was caused by trauma, insect bites, and Sweet’s syndrome. FPS had a sleeve-like shape in 20 cases, a plaque-like shape in 7, and combined in 5. Improvement was spontaneous in 4 cases. Under cimetidine monotherapy in five patients, complete remission was noticed in 3. The FPS notion gives prominence to the stereotypic tissue reaction pattern involving the subcutaneous septa and muscular fascia, emphasizes the etiologic and clinical diversity of the disorder, and notices the similar response to drug therapy in different clinical settings. The FPS concept is also supported by MRI studies showing that the hyperintense signal on MR T2-weighted images are not limited to the fascia but may extend to the adjacent adipose tissue and muscle fibers [6]. Furthermore, clinical and histological similarities are recognized between EF and morphea profunda: inflammation and sclerosis in the deep dermis, panniculus adiposus, fascia, and superficial muscle layers. EF and morphea profunda may occur in association, have similar autoimmune mechanisms, both have a 2–3-year course, and usually respond to corticosteroid treatment. Indeed, EF is often considered to belong to the severe side of the morphea spectrum [3].