Complete surgical excision is the treatment of choice, associated with an excellent long term clinical outcome.

It is important to exclude a tumor which is directly extending into the ear canal from the parotid salivary gland, especially when dealing with an adenoid cystic or mucoepidermoid carcinoma. This can be eliminated by clinical or imaging studies. Otherwise, the histologic differential diagnosis includes a ceruminous adenoma (a benign ceruminous gland tumor) or a neuroendocrine adenoma of the middle ear (middle ear adenoma).

It is important to separate hiberoma from adult rhabdomyoma, a granular cell tumor and a true liposarcoma.

Keratoacanthoma presents as a fleshy, elevated and nodular lesion with an irregular crater shape and a characteristic central hyperkeratotic core. Usually the patient will notice a rapidly growing dome-shaped tumor on sun-exposed skin.

If the entire lesion is removed, the pathologist will probably be able to differentiate between keratoacanthoma and squamous cell carcinoma. If only part of the lesion is removed, confident diagnosis may be impossible.

"FLCN" mutations are detected by sequencing in 88% of probands with Birt–Hogg–Dubé syndrome. This means that some people with the clinical diagnosis have mutations that are not detectable by current technology, or that mutations in another currently unknown gene could be responsible for a minority of cases. In addition, amplifications and deletions in exonic regions are also tested. Genetic testing can be useful to confirm the clinical diagnosis of and to provide a means of determining other at-risk individuals in a family even if they have not yet developed BHD symptoms.

The cutaneous manifestations of Birt–Hogg–Dubé were originally described as fibrofolliculomas (abnormal growths of a hair follicle), trichodiscomas (hamartomatous lesions with a hair follicle at the periphery, often found on the face), and acrochordons (skin tags). Cutaneous manifestations are confirmed by histology. Most individuals (89%) with BHD are found to have multiple cysts in both lungs, and 24% have had one or more episodes of pneumothorax. The cysts can be detected by chest CT scan. Renal tumors can manifest as multiple types of renal cell carcinoma, but certain pathological subtypes (including chromophobe, oncocytoma, and oncocytic hybrid tumors) are more commonly seen. Although the original syndrome was discovered on the basis of cutaneous findings, it is now recognized that individuals with Birt–Hogg–Dubé may only manifest the pulmonary and/or renal findings, without any skin lesions. Though these signs indicate BHD, it is only confirmed with a genetic test for FLCN mutations.

Wide, radical, complete surgical excision is the treatment of choice, with free surgical margins to achieve the best outcome and lowest chance of recurrence. Radiation is only used for palliation. In general, there is a good prognosis, although approximately 50% of patients die from disease within 3–10 years of presentation.

Intraductal papillary mucinous neoplasms can come to clinical attention in a variety of different ways. The most common symptoms include abdominal pain, nausea and vomiting. The most common signs patients have when they come to medical attention include jaundice (a yellowing of the skin and eyes caused by obstruction of the bile duct), weight loss, and acute pancreatitis. These signs and symptoms are not specific for an intraductal papillary mucinous neoplasm, making it more difficult to establish a diagnosis. Doctors will therefore often order additional tests.

Once a doctor has reason to believe that a patient may have an intraductal papillary mucinous neoplasm, he or she can confirm that suspicion using one of a number of imaging techniques. These include computerized tomography (CT), endoscopic ultrasound (EUS), and magnetic resonance cholangiopancreatography (MRCP). These tests will reveal dilatation of the pancreatic duct or one of the branches of the pancreatic duct. In some cases a fine needle aspiration (FNA) biopsy can be obtained to confirm the diagnosis. Fine needle aspiration biopsy can be performed through an endoscope at the time of endoscopic ultrasound, or it can be performed through the skin using a needle guided by ultrasound or CT scanning.

IPMN forms cysts (small cavities or spaces) in the pancreas. These cysts are visible in CT scans (X-ray computed tomography). However, many pancreatic cysts are benign (see Pancreatic disease).

A growing number of patients are now being diagnosed before they develop symptoms (asymptomatic patients). In these cases, the lesion in the pancreas is discovered accidentally (by chance) when the patient is being scanned (i.e. undergoing an ultrasound, CT or MRI scan) for another reason. Up to 6% of patients undergoing pancreatic resection did so for treatment of incidental IPMNs.

In 2011, scientists at Johns Hopkins reported that they have developed a gene-based test that can be used to distinguish harmless from precancerous pancreatic cysts. The test may eventually help patients with harmless cysts avoid needless surgery. Bert Vogelstein and his colleagues discovered that almost all of the precancerous cysts (intraductal papillary mucinous neoplasms) of the pancreas have mutations in the KRAS and/or the GNAS gene. The researchers then tested a total of 132 intraductal papillary mucinous neoplasms for mutations in KRAS and GNAS. Nearly all (127) had mutations in GNAS, KRAS or both. Next, the investigators tested harmless cysts such as serous cystadenomas, and the harmless cysts did not have GNAS or KRAS mutations. Larger numbers of patients must be studied before the gene-based test can be widely offered.

Serous cystic neoplasms can come to clinical attention in a variety of ways. The most common symptoms are very non-specific and include abdominal pain, nausea and vomiting. In contrast to many of the other tumors of the pancreas, patients rarely develop jaundice (a yellowing of the skin and eyes caused by obstruction of the bile duct), or weight loss. These signs and symptoms are not specific for a serous cystic neoplasm, making it more difficult to establish a diagnosis. Doctors will therefore often order additional tests.

Once a doctor has reason to believe that a patient may have serous cystic neoplasm, he or she can confirm that suspicion using one of a number of imaging techniques. These include computerized tomography (CT), endoscopic ultrasound (EUS), and magnetic resonance cholangiopancreatography (MRCP). These tests will reveal a cystic mass within the pancreas. The cysts do not communicate with the larger pancreatic ducts. In some cases a fine needle aspiration (FNA) biopsy can be obtained to confirm the diagnosis. Fine needle aspiration biopsy can be performed through an endoscope at the time of endoscopic ultrasound, or it can be performed through the skin using a needle guided by ultrasound or CT scanning.

A growing number of patients are now being diagnosed before they develop symptoms (asymptomatic patients). In these cases, the lesion in the pancreas is discovered accidentally (by chance) when the patient is being scanned (x-rayed) for another reason.

Excision of the entire lesion, with adequate margin, will remove the lesion, allow full tissue diagnosis, and leave a planned surgical wound which can usually be repaired with a good cosmetic result. However, removing the entire lesion (especially on the face) may present difficult problems of plastic reconstruction. (On the nose and face, Mohs surgery may allow for good margin control with minimal tissue removal, but many insurance companies require the definitive diagnosis of a malignancy "before" they are prepared to pay the extra costs of Mohs surgery.) Especially in more cosmetically-sensitive areas, and where the clinical diagnosis is reasonably certain, alternatives to surgery may include no treatment (awaiting spontaneous resolution).

On the trunk, arms, and legs, electrodesiccation and curettage often suffice to control keratoacanthomas until they regress. Other modalities of treatment include cryosurgery and radiotherapy; intralesional injection of methotrexate or of 5-fluorouracil have also been used.

Recurrence after electrodesiccation and curettage can occur; it can usually be identified and treated promptly with either further curettage or surgical excision.

Surgical excision of the lesion is done, and depending upon the clinical circumstances, this may or may not involve removal of the involved tooth. With incomplete removal, recurrence is common; some surgeons advocate curettage after extraction of teeth to decrease the overall rate of recurrence.

Epidermoid cysts are usually diagnosed when a person notices a bump on their skin and seeks medical attention. The definitive diagnosis is made after excision by a pathologist based on microscopic appearance of a cystic lesion lined by cornified epithelium containing lamellated keratin without calcifications. They can also be seen as isointense lesions on MRI or hyperintensities on FLAIR.

Diagnosis of EIN lesions is of clinical importance because of the increased risk of coexisting (39% of women with EIN will be diagnosed with carcinoma within one year) or future (the long term endometrial cancer risk is 45 times greater for a woman with EIN compared to one with only a benign endometrial histology) endometrial cancer. Diagnostic terminology is that used by pathologists, physicians who diagnose human disease by examination of histologic preparations of excised tissues. Critical distinctions in EIN diagnosis are separation from benign conditions such as benign endometrial hyperplasia (a field effect in endometrial tissue caused by excessive stimulation by the hormone estrogen), and cancer.

The spectrum of disease which must be distinguished from EIN (Table II) includes benign endometrial hyperplasia and carcinoma:

Table II: Disease classes that need to be distinguished from EIN.

EIN may be diagnosed by a trained pathologist by examination of tissue sections of the endometrium. All of the following diagnostic criteria must be met in a single area of one tissue fragment to make the diagnosis (Table III).

Table III: EIN diagnosis.

Fordyce spots are completely benign and require no treatment. Often their presence is considered normal anatomic variance rather than a true medical condition.

The treatment is simple excision and exclusion of a malignant neoplasm.

The treatment of choice for main-duct IPMNs is resection due to approximately 50% chance of malignancy. Side-branch IPMNs are occasionally monitored with regular CT or MRIs, but most are eventually resected, with a 30% rate of malignancy in these resected tumors. Survival 5 years after resection of an IPMN without malignancy is approximately 80%, 85% with malignancy but no lymph node spread and 0% with malignancy spreading to lymph nodes. Surgery can include the removal of the head of the pancreas (a pancreaticoduodenectomy), removal of the body and tail of the pancreas (a distal pancreatectomy), or rarely removal of the entire pancreas (a total pancreatectomy). In selected cases the surgery can be performed using minimally invasive techniques such as laparoscopy or robotic surgery. A study using Surveillance, Epidemiology, and End Result Registry (SEER) data suggested that increased lymph node counts harvested during the surgery were associated with better survival in invasive IPMN patients.

Trichilemmoma (also known as "tricholemmoma") is a benign cutaneous neoplasm that shows differentiation toward cells of the outer root sheath. The lesion is often seen in the face and neck region. Multifocal occurrence is associated with Cowden syndrome, in which hamartomatous intestinal polyposis is seen in conjunction with multiple tricholemmoma lesions.

Treatment of small melanomas is often not necessary, but large tumors can cause discomfort and are usually surgically removed. Cisplatin and cryotherapy can be used to treat small tumors less than 3 centimeters, but tumors may reoccur. Cimetidine, a histamine stimulator, can cause tumors to regress in some horses, but may take up to 3 months to produce results and multiple treatments may be needed throughout the horse's life. There are few viable treatment options for horses with metastatic melanoma. However, gene therapy injections utilizing interleukin-12 and 18-encoding DNA plasmids have shown promise in slowing the progression of tumors in patients with metastatic melanoma.

An acanthoma is a skin neoplasm composed of squamous or epidermal cells. It is located in the prickle cell layer.

Types of acanthoma include pilar sheath acanthoma, a benign follicular tumor usually of the upper lip; clear cell acanthoma, a benign tumor found most frequently on the legs; and Degos acanthoma, often confused with but unrelated to Degos disease.

Lymphoma is the most common type of blood-related cancer in horses and while it can affect horses of all ages, it typically occurs in horses aged 4–11 years.

These lesions rarely require surgery unless they are symptomatic or the diagnosis is in question. Since these lesions do not have malignant potential, long-term observation is unnecessary. Surgery can include the removal of the head of the pancreas (a pancreaticoduodenectomy), removal of the body and tail of the pancreas (a distal pancreatectomy), or rarely removal of the entire pancreas (a total pancreatectomy). In selected cases the surgery can be performed using minimally invasive techniques such as laparoscopy.

Surgical excision is required to treat a trichilemmal cyst. The method of treatment varies depending on the physician's training. Most physicians perform the procedure under local anesthetic. Others prefer a more conservative approach. This involves the use of a small punch biopsy about 1/4 the diameter of the cyst. The punch biopsy is used to enter the cyst cavity. The content of the cyst is emptied, leaving an empty sac. As the pilar cyst wall is the thickest and most durable of the many varieties of cysts, it can be grabbed with forceps and pulled out of the small incision. This method is best performed on cysts larger than a pea which have formed a thick enough wall to be easily identified after the sac is emptied. Small cysts have walls that are thin, and easily fragmented on traction. This increases the likelihood of cyst recurrence. This method often results in only a small scar, and very little if any bleeding.

Most doctors consider this a normal physiological phenomenon and advise against treatment.

Microvenular hemangioma (also known as "Microcapillary hemangioma") is an acquired benign vascular neoplasm that presents as an asymptomatic, slowly growing, 0.5- to 2.0 cm reddish lesion on the forearms or other sites of young to middle-aged adults.

A vascular tissue neoplasm is a tumor arising from endothelial cells, the cells that line the wall of blood vessels and lymphatic vessels, as well as the heart. Vascular tissue neoplasms is a group containing tumors with the same tissue origin; in other words, it denotes histological classification, rather than anatomic (i.e. where in the body the neoplasm is found) or clinical one. They can occur everywhere in the body where vessels are to be found.