In breast pathology, a radial scar of the breast, formally radial scar of the breast, is a benign breast lesion that can radiologically mimic malignancy, i.e. cancer.

Radial scar is associated with atypia and/or malignancy and may be an independent risk factor for the development of carcinoma in either breast.

Pseudomelanoma (also known as a "recurrent melanocytic nevus", and "recurrent nevus") is a cutaneous condition in which melantic skin lesions clinically resemble a superficial spreading melanoma at the site of a recent shave removal of a melanocytic nevus.

Histologically, keloids are fibrotic tumors characterized by a collection of atypical fibroblasts with excessive deposition of extracellular matrix components, especially collagen, fibronectin, elastin, and proteoglycans. Generally, they contain relatively acellular centers and thick, abundant collagen bundles that form nodules in the deep dermal portion of the lesion. Keloids present a therapeutic challenge that must be addressed, as these lesions can cause significant pain, (itching), and physical disfigurement. They may not improve in appearance over time and can limit mobility if located over a joint.

Keloids affect both sexes equally, although the incidence in young female patients has been reported to be higher than in young males, probably reflecting the greater frequency of earlobe piercing among women.

The frequency of occurrence is 15 times higher in highly pigmented people. African descendant people have increased risk of keloid occurrences.

Mechanical tension on a wound has been identified as a leading cause for hypertrophic scar formation.

When a normal wound heals, the body produces new collagen fibres at a rate which balances the breakdown of old collagen. Hypertrophic scars are red and thick and may be itchy or painful. They do not extend beyond the boundary of the original wound, but may continue to thicken for up to six months. They usually improve over one or two years, but may cause distress due to their appearance or the intensity of the itching; they can also restrict movement if they are located close to a joint.

Some people have an inherited tendency to this type of scarring, for example, those with Ehlers–Danlos syndrome, classic type. It is not possible to completely prevent hypertrophic scars, so those with a history of them should inform their doctor or surgeon if they need surgery. Scar therapies may speed up the process of change from a hypertrophic scar to a flatter, paler one.

Persons of any age can develop a keloid. Children under 10 are less likely to develop keloids, even from ear piercing. Keloids may also develop from Pseudofolliculitis barbae; continued shaving when one has razor bumps will cause irritation to the bumps, infection, and over time keloids will form. Persons with razor bumps are advised to stop shaving in order for the skin to repair itself before undertaking any form of hair removal. The tendency to form keloids is speculated to be hereditary. Keloids can tend to appear to grow over time without even piercing the skin, almost acting out a slow tumorous growth; the reason for this tendency is unknown.

Extensive burns, either thermal or radiological, can lead to unusually large keloids; these are especially common in firebombing casualties, and were a signature effect of the atomic bombings of Hiroshima and Nagasaki.

True incidence and prevalence of keloid in United States is not known. Indeed, there has never been a population study to assess the epidemiology of this disorder. In his 2001 publication, Marneros stated that “reported incidence of keloids in the general population ranges from a high of 16% among the adults in Zaire to a low of 0.09% in England,” quoting from Bloom’s 1956 publication on heredity of keloids. We do however know, from clinical observations that the disorder is more common among Africans, African Americans and Asians with unreliable and very wide estimated prevalence rates ranging from 4.5-16%. Thorough and scientific population and epidemiology studies of this disorder are desperately needed.

A hypertrophic scar is a cutaneous condition characterized by deposits of excessive amounts of collagen which gives rise to a raised scar, but not to the degree observed with keloids. Like keloids, they form most often at the sites of pimples, body piercings, cuts and burns. They often contain nerves and blood vessels. They generally develop after thermal or traumatic injury that involves the deep layers of the dermis and express high levels of TGF-β.

The presence of a radial scar on imaging mandates a percutaneous core biopsy for histologic diagnosis. Excisional biopsy is usually recommended for radial scar, although it has been argued that core biopsy evaluation and surveillance may be appropriate in selected patients.

The melanocytes left behind in the wound regrow in an abnormal pattern. Rather than the even and regular lace like network, the pigments tends to grow in streaks of varying width within the scar. This is often accompanied by scarring, inflammation, and blood vessel changes – giving both the clinical and histologic impression of a melanoma or a severe dysplastic nevus. When the patient is reexamined years later without the assistance of the original biopsy report, the physician will often require the removal of the scar with the recurrent nevus to assure that a melanoma is not missed.

Superficial spreading melanoma (also known as "superficially spreading melanoma") (SSM) is usually characterized as the most common form of cutaneous melanoma in Caucasians. The average age at diagnosis is in the fifth decade, and it tends to occur on sun-exposed skin, especially on the backs of males and lower limbs of females.

Malformations of the upper extremities can occur In the third to seventh embryonic week. In some cases the TPT is hereditary. In these cases, there is a mutation on chromosome 7q36. If the TPT is hereditary, it is mostly inherited as an autosomal dominant trait, non-opposable and bilateral. The sporadic cases are mostly opposable and unilateral.

Triphalangeal thumb can occur in syndromes but it can also be isolated. The triphalangeal thumb can appear in combination with other malformations or syndromes.

Syndromes include:

- Holt-Oram syndrome

- Aase syndrome

- Blackfan-Diamond syndrome

- Townes-Brocks syndrome

Malformations include:

- Radial polydactyly

- Syndactyly

- Claw-like hand or foot

Burn scar contracture refers to the tightening of the skin after a second or third degree burn. When skin is burned, the surrounding skin begins to pull together, resulting in a contracture. It needs to be treated as soon as possible because the scar can result in restriction of movement around the injured area.

FNH is not a true neoplasm; it is believed to result from localized hyperplastic hepatocyte response to an underlying congenital arteriovenous malformation. It consists of normal liver constituents in an abnormally organized pattern, grows in a stellate pattern and may display central necrosis when large. Additionally evidence suggests that the incidence of FNH is related to oral contraceptive use.

Focal nodular hyperplasia (FNH) is a benign tumor of the liver (hepatic tumor), which is the second most prevalent tumor of the liver (the first is hepatic hemangioma). It is usually asymptomatic, rarely grows or bleeds, and has no malignant potential. This tumour was once often resected because it was difficult to distinguish from hepatic adenoma, but with modern multiphase imaging is usually now diagnosed by strict imaging criteria and not resected.

Dysmelia can be caused by

- inheritance of abnormal genes, e.g. polydactyly, ectrodactyly or brachydactyly, symptoms of deformed limbs then often occur in combination with other symptoms (syndromes)

- external causes during pregnancy (thus not inherited), e.g. via amniotic band syndrome

- teratogenic drugs (e.g. thalidomide, which causes phocomelia) or environmental chemicals

- ionizing radiation (nuclear weapons, radioiodine, radiation therapy)

- infections

- metabolic imbalance

Collagenous spherulosis, also mucinous spherulosis and simply spherulosis, is a benign finding in breast pathology. It is almost always an incidental finding, though it is occasionally associated with calcifications, which may lead to a biopsy.

Burn scar contractures do not go away on their own, although may improve with the passage of time, with occupationaltherapy and physiotherapy, and with splinting. If persistent the person may need the contracture to be surgically released. Techniques may include local skin flaps (z-plasty) or skin grafting (full thickness or split thickness). There are also pharmacy and drug-store treatments that can be used to help scar maturation, especially silicone gel treatments. Prevention of contracture formation is key. For instance, in the case of a burned hand one would splint the hand and wrap each finger individually. In the instance of burns on the neck, hyperextension of the neck (i.e. no use of pillows) should be maintained during the healing process. Carbon dioxide laser therapy is now also used to aid in the loosening of surrounding skin, although is yet to form as part of an official global rehabilitation program.

Treatment is by excisional biopsy, wide local excision and possibly sentinel node biopsy. Spread of disease to local lymph nodes or distant sites (typically brain, bone, skin and lung) marks a decidedly poor prognosis.

The Wassel classification is used to categorise radial polydactyly, based upon the most proximal level of skeletal duplication.

Nodular melanoma (NM) is the most aggressive form of melanoma. It tends to grow more rapidly in thickness (penetrate the skin) than in diameter. Instead of arising from a pre-existing mole, it may appear in a spot where a lesion did not previously exist . Since NM tends to grow in depth more quickly than it does in width, and can occur in a place that did not have a previous lesion, the prognosis is often worse because it takes longer for a person to be aware of the changes. NM is most often darkly pigmented; however, some NM lesions can be light brown, multicolored or even colorless (non-pigmented). A light-colored or non-pigmented NM lesion may escape detection because the appearance is not alarming, however an ulcerated and/or bleeding lesion is common. Polypoid melanoma is a virulent variant of nodular melanoma.

The microscopic hallmarks are:

- Dome-shaped at low power

- Epidermis thin or normal

- Dermal nodule of melanocytes with a 'pushing' growth pattern

- No "radial growth phase"

A neuroma (plural: neuromata or neuromas) is a growth or tumor of nerve tissue. Neuromas tend to be benign (i.e. not cancerous); many nerve tumors, including those that are commonly malignant, are nowadays referred to by other terms.

Neuromas can arise from different types of nervous tissue, including the nerve fibers and their myelin sheath, as in the case of genuine neoplasms (growths) like ganglioneuromas and neurinomas.

The term is also used to refer to any swelling of a nerve, even in the absence of abnormal cell growth. In particular, traumatic neuroma results from trauma to a nerve, often during a surgical procedure. Morton's neuroma affects the foot.

Neuromas can be painful, or sometimes, as in the case of acoustic neuromas, can give rise to other symptoms.

Therapies for metastatic melanoma include the biologic immunotherapy agents ipilimumab, pembrolizumab, and nivolumab; BRAF inhibitors, such as vemurafenib and dabrafenib; and a MEK inhibitor trametinib.

The exact cause of Kienböck's is not known, though there are thought to be a number of factors predisposing a person to Kienböck's.

Recent studies have made a correlation between Kienböck's sufferers and Western European ancestry, but no definitive link can be positively confirmed.

The necrosis of the lunate bone can frequently be traced to a trauma to the wrist, like a compound fracture, which could cause the lunate's blood supply to be interrupted. Blood flows to the lunate through several arteries, each supplying a percentage. When one of these pathways is severed, the likelihood the patient will develop necrosis increases.

Despite a preponderance of evidence, no particular cause has been conclusively verified.

Data exists on the internet that most people suffering from Kienböck's are affected in their dominant hand, though about one-third of sufferers report the condition in their non-dominant hand. In very few cases have there been people that have acquired it in both wrists.

Kienböck's disease is classified as a "rare disorder," meaning that it affects fewer than 200,000 people in the U.S. population.

Many Kienböck's patients are frustrated by the lack of consensus among hand surgeons about optimal treatments for Kienböck's. No matter what the disease's stage of progression, there is no one best treatment, and the decision is often based partially, or even mostly, on incidental factors such as the patient's pain tolerance, the patient's desire to return to active use of the hand (such as in manual occupations), and the surgeon's level of expertise with different treatments.

Though, since each case of Kienböck's is different, the makeup of the wrist and arm bones are important factors which are individualized to each patient. Therefore, one surgery will never be able to solve all the problems associated with the disease. Thus, no consensus can be reached among surgeons.

The condition has an incidence of 1 in every 500 live births. Postaxial hand polydactyly is a common isolated disorder in African black children, and autosomal dominant transmission is suspected. Postaxial polydactyly is more frequent in native Africans living in the Eastern and Central than the Caucasians and Mongoloids and is more frequent in male children. In contrast, postaxial polydactyly seen in white children is usually syndromic and associated with an autosomal recessive transmission. One study by Finley et al. combined data from Jefferson County, Alabama, United States and Uppsala County, Sweden. This study showed incidence of all types of polydactyly to be 2.3 per 1000 in Caucasian males, 0.6 per 1000 in Caucasian females, 13.5 per 1000 in African males, and 11.1 per 1000 in African females.

Lipohypertrophy is a medical term that refers to a lump under the skin caused by accumulation of extra fat at the site of many subcutaneous injections of insulin. It may be unsightly, mildly painful, and may change the timing or completeness of insulin action. It is a common, minor, chronic complication of diabetes mellitus.

Typical injection site hypertrophy is several inches or cm across, smoothly rounded, and somewhat firmer than ordinary subcutaneous fat. There may be some scar tissue as well, but the major component is adipose tissue, as insulin exerts a hypertrophic effect on adipose cells. To avoid lipohypertrophy, persons with diabetes mellitus who inject insulin daily for an extended period of time are advised to "rotate" their injections among several areas (usually upper, outer arms, outer thighs, abdomen below and around the umbilicus, and the upper parts of the buttocks). Rotation charts are often provided as part of diabetes education to help prevent lipohypertrophy.

Lipohypertrophy usually will gradually disappear over months if injections in the area are avoided.

It is a common misconception that the lump is largely scar tissue, as injection site hypertrophy is much rarer and milder with injections of other hormones and medications which lack the specific ability of insulin to stimulate adipose hypertrophy.

In a sense, the "opposite" of injection site lipohypertrophy is injection site lipoatrophy, in which the subcutaneous fat around an injected area "melts away" over a few weeks or months, leaving unsightly, well-demarcated depressions in the skin. The mechanism of this local lipoatrophy is not understood and may involve autoimmunity or local inflammation.