: 636

Hereditary
Epidermolytic hyperkeratosis (also known as "Bullous congenital ichthyosiform erythroderma," "Bullous ichthyosiform erythroderma,": 482  or "bullous congenital ichthyosiform erythroderma of Brocq") is a rare skin disease in the ichthyosis family affecting around 1 in 250,000 people. It involves the clumping of keratin filaments. : 562 
Multiple minute digitate hyperkeratosis, a rare cutaneous condition, with about half of cases being familial
Focal acral hyperkeratosis (also known as "Acrokeratoelastoidosis lichenoides,") is a late-onset keratoderma, inherited as an autosomal dominant condition, characterized by oval or polygonal crateriform papules developing along the border of the hands, feet, and wrists. : 509 
Keratosis pilaris appears similar to gooseflesh, is usually asymptomatic and may be treated by moisturizing the skin. Other
Hyperkeratosis lenticularis perstans (also known as "Flegels disease") is a cutaneous condition characterized by rough, yellow-brown keratotic, flat-topped papules. : 639

In mucous membranes
The term hyperkeratosis is often used in connection with lesions of the mucous membranes, such as leukoplakia. Because of the differences between mucous membranes and the skin (e.g. keratinizing mucosa does not have a stratum lucidum and non keratinizing mucosa does not have this layer or normally a stratum corneum or a stratum granulosum), sometimes specialized texts give slightly different definitions of hyperkeratosis in the context of mucosae. Examples are "an excessive formation of keratin (e.g., as seen in leukoplakia)" and "an increase in the thickness of the keratin layer of the epithelium, or the presence of such a layer in a site where none would normally be expected."
Peritonitis is inflammation of the localized or generalized peritoneum, the lining of the inner wall of the abdomen and cover of the abdominal organs. Symptoms may include severe pain, swelling of the abdomen, fever, or weight loss. One part or the entire abdomen may be tender. Complications may include shock and acute respiratory distress syndrome.Causes include perforation of the intestinal tract, pancreatitis, pelvic inflammatory disease, stomach ulcer, cirrhosis, or a ruptured appendix. Risk factors include ascites (the abnormal build-up of fluid in the abdomen) and peritoneal dialysis. Diagnosis is generally based on examination, blood tests, and medical imaging.Treatment often includes antibiotics, intravenous fluids, pain medication, and surgery. Other measures may include a nasogastric tube or blood transfusion. Without treatment death may occur within a few days. About 20% of people with cirrhosis who are hospitalized have peritonitis. Signs and symptoms
Abdominal pain
The main manifestations of peritonitis are acute abdominal pain, abdominal tenderness, abdominal guarding, rigidity, which are exacerbated by moving the peritoneum, e.g., coughing (forced cough may be used as a test), flexing ones hips, or eliciting the Blumberg sign (meaning that pressing a hand on the abdomen elicits less pain than releasing the hand abruptly, which will aggravate the pain, as the peritoneum snaps back into place). Rigidity is highly specific for diagnosing peritonitis (specificity: 76–100%). The presence of these signs in a person is sometimes referred to as peritonism. The localization of these manifestations depends on whether peritonitis is localized (e.g., appendicitis or diverticulitis before perforation), or generalized to the whole abdomen.