<prompt> All of the following skin conditions are considered as skin markers for internal malignancy exceptAcanthosis nigricansDermatomyositisBullous pemphigoidPemphigus valgaris  <response>: Acanthosis nigricans, brown to grey - black velvety thickening of the skin in flexural areas, is caused by insulin resistance, obesity, drugs and underlying malignancy esp. of the stomach and large intestine.Dermatomyositis results from an immune-mediated process triggered by various factors such as malignancy ovarian carcinoma, nasopharyngeal carcinoma, mycosis fungoides and lymphoproliferative malignancies , drugs and infectious agents in genetically predisposed individuals. Bullous pemphigoid BP is an acquired, autoimmune, sub-epidermal blistering disease. It is also associated with underlying malignancies SCC,RCCReference : page 303,274,283 IADVLs Concise Textbook of Dermatology 