In contrast to weight loss from inadequate caloric intake, cachexia causes predominantly muscle loss instead of fat loss and it is not as responsive to nutritional intervention. Cachexia can significantly compromise quality of life and functional status and is associated with poor outcomes. Sarcopenia
Sarcopenia is the degenerative loss of skeletal muscle mass, quality, and strength associated with aging. This involves muscle atrophy, reduction in number of muscle fibers and a shift towards "slow twitch" or type I skeletal muscle fibers over "fast twitch" or type II fibers. The rate of muscle loss is dependent on exercise level, co-morbidities, nutrition and other factors. There are many proposed mechanisms of sarcopenia and is considered to be the result of changes in muscle synthesis signalling pathways and gradual failure in the satellite cells which help to regenerate skeletal muscle fibers, but is incompletely understood.Sarcopenia can lead to reduction in functional status and cause significant disability but is a distinct condition from cachexia although they may co-exist. In 2016 an ICD code for sarcopenia was released, contributing to its acceptance as a disease entity. Intrinsic muscle diseases
Muscle diseases, such as muscular dystrophy, amyotrophic lateral sclerosis (ALS), or myositis such as inclusion body myositis can cause muscle atrophy. Central nervous system damage
Damage to neurons in the brain or spinal cord can cause prominent muscle atrophy. This can be localized muscle atrophy and weakness or paralysis such as in stroke or spinal cord injury. More widespread damage such as in traumatic brain injury or cerebral palsy can cause generalized muscle atrophy.
A corpus luteum cyst is a type of ovarian cyst which may rupture about the time of menstruation, and take up to three months to disappear entirely. A corpus luteum cyst rarely occurs in women over the age of 50, because eggs are no longer being released after menopause. Corpus luteum cysts may contain blood and other fluids. The physical shape of a corpus luteum cyst may appear as an enlargement of the ovary itself,  rather than a distinct mass -like growth on the surface of the ovary. Signs and symptoms
Corpus luteum cysts are a normal part of the menstrual cycle. They can, however, grow to almost 10 cm (4 inches) in diameter and have the potential to bleed into themselves or twist the ovary, causing pelvic or abdominal pain. It is possible the cyst may rupture, causing internal bleeding and pain. This pain typically disappears within a few days of the rupture. If the corpus luteum becomes large it may cause ovarian torsion, where the ovary twists and blood flow is cut off. Ovarian torsion is rare and is accompanied by severe pain. Pathophysiology
This type of functional cyst occurs after an egg has been released from a follicle. The follicle then becomes a secretory gland that is known as the corpus luteum. The ruptured follicle begins producing large quantities of estrogen and progesterone in preparation for conception. If a pregnancy doesnt occur, the corpus luteum usually breaks down and disappears.