Metaplasia Of Sebaceous Glands Research Articles

S1897 Sebaceous Gland Metaplasia: An Enigmatic but Harmless Entity

S1897 Sebaceous Gland Metaplasia: An Enigmatic but Harmless Entity

TCDD-induced activation of aryl hydrocarbon receptor regulates the skin stem cell population

The environmental toxin 2,3,7,8 tetrachlorodibenzo p-dioxin (TCDD) plays an important role in the development of chloracne. Chloracne is characterized by hyperkeratosis of the interfollicular squamous epithelium and metaplasia of sebaceous glands. Dysregulation of keratinocyte terminal differentiation leading to accelerated formation of the cornified envelope as a result of TCDD-mediated aryl hydrocarbon receptor (AHR) activation has been implicated as one of the molecular pathogenic mechanisms contributing to the development of chloracne. In addition, chloracne is characterized by altered skin stem cell characteristics, and it has been speculated that the phenotype of chloracne closely matches that of c-Myc overexpressing transgenic mice. Therefore, we sought to determine whether TCDD plays a role in regulation of the skin stem cell population. We have proposed in this report that TCDD may directly or indirectly (via AHR receptor cross-talk) upregulate c-Myc via epidermal growth factor receptor–extracellular signal regulated kinase (EGFR–ERK) axis stimulation, which may correspond with an increase in human epidermal stem cell activation and differentiation of EPSCs into keratinocytes, with eventual depletion of the epidermal stem cell compartment of the skin. Thus, TCDD may cause increased epidermal stem cell turnover during chloracne.

Sebaceous Gland Metaplasia in the Oesophagus of a Cynomolgus Monkey (Macaca fascicularis)

Microscopical evaluation of tissues from a mature female cynomolgus monkey assigned to a 13-week oral toxicity study revealed nests of sebaceous cells within the mucosa of the distal oesophagus. The sebaceous cell nests showed normal differentiation from basally-oriented seboblasts to centrally-orientated mature sebocytes. No excretory ducts were found, but solitary or small groups of vacuolated sebocytes were present in the overlying normal, non-keratinized squamous epithelium. The finding of sebaceous cells, of presumed ectodermal origin, in the oesophageal mucosa, which is of endodermal origin, is of scientific interest. Different theories may explain the existence of this peculiarity, but sebaceous gland metaplasia is the most plausible. The mucosal change was thought to be unrelated to treatment and is the first case of sebaceous gland metaplasia reported in the oesophagus of a non-human primate.

개의 안검에 존재하는 내검판선 및 외검판선에서 발생한 선암종

본 증례는 4년령의 암컷 비글종에서 발생한 것으로 점진적인 안구돌출증을 비롯하여 왼쪽 하안구 부속기에 발생한 직경 1.4 cm 의 종양을 가지고 있었다. 종양의 병리조직학적 검경에서 증생된 종양 세포들이 소엽 및 섬유성 격벽으로 구분되는 관통상의 구조를 나타내고 있었다. 잘 분화된 피지선은 다양한 크기의 소엽을 형성하고 있으며 비만세포 및 단핵 염증세포의 침윤이 관찰되었다. 관강 내에는 이러한 관성구조의 정점부위에서 탈락되어 나온 호염성 불질이 관찰되었으며 일부 관성구조는 경도의 화생을 나타내고 있었다. 조직면역염색에서 세포집단은 <TEX>${\alpha}-SMA$</TEX>와 vimentin에 양성 반응을 나타내었다. 따라서 본 원발성 종양은 안검에서 발생한 내검판선 및 외검판선 유래의 선암종으로 진단되었으며 침윤되고 있는 안구내 종양은 악성 혼합종으로 진단되었다. A 4-year-old female beagle with progressive exophthalmos and which had a neoplastic mass with diameter of 1.4 cm in the left lower ocular adnexa. Histologically, the mass was composed of hyper-plastic lobules and tubular structures separated by fibrous septum. The well differentiated sebaceous gland forming various sized lobules, and infiltration of mast cells and mononuclear inflammatory cells were observed. Apical decapitation secretion of these tubular structures with basophilic materials in their lumen showed mild sebaceous gland metaplasia. Immunohistochemical studying, cell groups were positive in <TEX>${\alpha}-SMA$</TEX> and vimentin. The primary tumor was diagnosed as adenocarcinoma originated from moll gland and meibomian gland of the eyelid, and the infiltrating intraocular neoplasm was diagnosed as a malignant mixed tumor.

Sebaceous Gland Metaplasia in a Mammary Fibroadenoma Developing in a Female Donryu Rat.

A mammary fibroadenoma with prominent sebaceous gland-like structures in a female Donryu rat aged 67 weeks was immunohistochemically investigated. The tumor demonstrated a mixture of both epithelial and connective tissue components, the former having both single- and multi-layered patterns. Characteristic sebaceous gland-like structures were apparent in connection with multi-layered epithelium. Area of single-layered epithelium comprised well-differentiated myoepithelial cells positive for alpha-smooth muscle actin (alpha-SMA), similar to mammary ducts. In contrast, many epithelial cells on the basal sides of multi-layers were negative for alpha-SMA, but positive for cytokeratin 14 (CK14), suggesting pluripotency. From these results, we diagnosed this case as a mammary fibroadenoma with sebaceous gland metaplasia.

Histologic Changes Produced by 2,3,7,8-Tetrachlorodibenzo-p-dioxin in the Skin of Mice Carrying Mutations That Affect the Integument

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) produces epidermal hyperplasia and hyperkeratosis, squamous metaplasia of the sebaceous gland, and keratinized cyst formation in 8 strains of mice with the recessive mutation, hairless (hr/hr). The extent of these histologic changes is dependent on the genetic background. No cutaneous lesions are produced in haired (hr/+) mice. In examination of mice with 7 other mutations affecting the integument, TCDD produced similar histologic skin changes in cryptothrix, nude, plucked, and atrichosis; a marginal squamous metaplasia of sebaceous glands in Repeated epilation, and had no effect in fur deficient and Naked mutants. These genetically determined epidermal responses are discussed in light of the mechanism of action of TCDD.

Response of murine epidermis to 2,3,7,8-tetrachlorodibenzo- p-dioxin: Interaction of the Ah and hr loci

2,3,7,8-Tetrachlorodibenzo- p-dioxin (TCDD) and related halogenated aromatic hydrocarbons produce epidermal hyperplasia, hyperkeratosis and sebaceous gland metaplasia in the skin of mice bearing the recessive mutation ( hr/hr) hairless. This response is mediated through the cytosol receptor protein: the structure-activity relationship for receptor binding corresponds to that for production of the skin lesion, and these histopathological changes segregate with the genetic polymorphism at the Ah locus, the locus determining the cytosol receptor. In HRS/J mice, an inbred strain segregating for the hr locus, both hairless ( hr/hr) and haired ( hr/ +) mice possess the high-affinity cytosol receptor and respond to TCDD with the induction of epidermal aryl hydrocarbon hydroxylase activity, a receptor-mediated biochemical response; however, only hr/hr mice develop the proliferative/metaplastic skin response. We propose a genetic model for the interaction of the Ah and hr loci, to account for the differential response to TCDD observed in the skin of HRS/ J hr/hr and hr/ + mice.

Toxic Effects of Marihuana Tar on Mouse Skin

Tar obtained from Cannabis sativa was dissolved in acetone and painted on albino Swiss mice and black and white f1, hybrid mice. Microscopic examination of the skin showed squamous metaplasia of the sebaceous glands and hyperkeratosis, acanthosis, and in some cases, enlargement and hyperehromasia of nuclei and poor cellular polarity in the squamous epithelium. Since metaplasia of sebaceous glands correlates with carcinogenicity, C sativa tar might prove to be carcinogenic.