Definitive diagnosis of Merkel cell carcinoma (MCC) requires examination of biopsy tissue. An ideal biopsy specimen is either a punch biopsy or a full-thickness incisional biopsy of the skin including full-thickness dermis and subcutaneous fat. In addition to standard examination under light microscopy, immunohistochemistry (IHC) is also generally required to differentiate MCC from other morphologically similar tumors such as small cell lung cancer, the small cell variant of melanoma, various cutaneous leukemic/lymphoid neoplasms, and Ewing's sarcoma. Similarly, most experts recommend longitudinal imaging of the chest, typically a CT scan, to rule out that the possibility that the skin lesion is a cutaneous metastasis of an underlying small cell carcinoma of the lung.

Diagnosis is confirmed via biopsy of the tissue(s) suspected to be affected by SCC. For the skin, look under skin biopsy.

The pathological appearance of a squamous cell cancer varies with the depth of the biopsy. For that reason, a biopsy including the subcutaneous tissue and basalar epithelium, to the surface is necessary for correct diagnosis. The performance of a shave biopsy (see skin biopsy) might not acquire enough information for a diagnosis. An inadequate biopsy might be read as actinic keratosis with follicular involvement. A deeper biopsy down to the dermis or subcutaneous tissue might reveal the true cancer. An excision biopsy is ideal, but not practical in most cases. An incisional or punch biopsy is preferred. A shave biopsy is least ideal, especially if only the superficial portion is acquired.

The following methods are employed in the treatment of basal-cell carcinoma (BCC):

Basal-cell carcinoma is a common skin cancer and occurs mainly in fair-skinned patients with a family history of this cancer. Sunlight is a factor in about two-thirds of these cancers; therefore, doctors recommend sunscreens with at least SPF 30. One-third occur in non-sun-exposed areas; thus, the pathogenesis is more complex than UV exposure as "the" cause.

The use of a chemotherapeutic agent such as 5-Fluorouracil or imiquimod, can prevent development of skin cancer. It is usually recommended to individuals with extensive sun damage, history of multiple skin cancers, or rudimentary forms of cancer (i.e., solar keratosis). It is often repeated every 2 to 3 years to further decrease the risk of skin cancer.

This type of cancer occurs most often in Caucasians between 60 and 80 years of age, and its rate of incidence is about twice as high in males as in females. There are roughly 1,500 new cases of MCC diagnosed each year in the United States, as compared to around 60,000 new cases of melanoma and over 1 million new cases of nonmelanoma skin cancer. MCC is sometimes mistaken for other histological types of cancer, including basal cell carcinoma, squamous cell carcinoma, malignant melanoma, lymphoma, and small cell carcinoma, or as a benign cyst. Researchers believe that exposure to sunlight or ultraviolet light (such as in a tanning bed) may increase the risk of developing this disease. Similar to melanoma, the incidence of MCC in the US is increasing rapidly.

Immunosuppression can profoundly increase the odds of developing Merkel-cell carcinoma. Merkel-cell carcinoma occurs 30 times more often in people with chronic lymphocytic leukemia and 13.4 times more often in people with advanced HIV as compared to the general population; solid organ transplant recipients have a 10-fold increased risk compared to the general population.

The long-term outcome of squamous cell carcinomas is dependent upon several factors: the sub-type of the carcinoma, available treatments, location(s) and severity, and various patient health-related variables (accompanying diseases, age, etc.). Generally, the long-term outcome is positive, as less than 4% of Squamous cell carcinoma cases are at risk of metastasis. Some particular forms of squamous cell carcinomas have a higher mortality rate. One study found squamous cell carcinoma of the penis had a much greater rate of mortality than some other forms of squamous cell carcinoma, that is, about 23%, although this relatively high mortality rate may be associated with possibly latent diagnosis of the disease due to patients avoiding genital exams until the symptoms are debilitating, or refusal to submit to a possibly scarring operation upon the genitalia. Squamous cell carcinoma occurring in the organ transplant population is also associated with a higher risk of mortality.

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.

a) Surgical resection is mainstay of treatment, whenever possible. If tumor is completely removed, post-operative radiation therapy is typically not needed since acinic cell is considered a low-grade histology. Post-operative radiation therapy for acinic cell carcinoma is used if: 1) margins are positive, 2) incomplete resection, 3) tumor invades beyond gland, 4) positive lymph nodes.

b) Neutron beam radiation

c) Conventional radiation

d) Chemotherapy

Photodynamic therapy, cryotherapy (freezing), or local chemotherapy (with 5-fluorouracil) are favored by some clinicians over . Because the cells of Bowen's disease have not invaded the dermis, it has a much better prognosis than invasive squamous cell carcinoma.

Good results have been noted with the use of imiquimod for Bowen's disease, including on the penis (erythroplasia of Queyrat), although imiquimod is not (as of 2013) approved by the U.S. Food and Drug Administration for the treatment of any type of squamous cell carcinoma, and serious side effects can occur with use of imiquimod.

Prognosis is good for acinic cell carcinoma of the parotid gland, with five-year survival rates approaching is 90%, and 20-year survival exceeding 50%. Patients with acinic cell carcinomas with high grade transformation (sometimes also called dedifferentiation) have significantly worse survival.

The prognosis of an acinic cell carcinoma originating in the lung is much more guarded than cases of this rare histotype occurring in most other organs, but is still considerably better than for other types of lung cancer.

This type of carcinoma is commonly managed by local resection, cryotherapy, topical chemotherapy, and radiotherapy. Multimodal therapy has been shown to improve both visual prognosis and survival.

Mohs micrographic surgery has become the treatment of choice for this form of cancer. When used as the primary treatment modality for sebaceous carcinoma of the eyelid, Mohs surgery is associated with significantly lower local and distant recurrence rates.

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).

The risk of renal cell carcinoma can be reduced by maintaining a normal body weight.

Recurrence is common, although the recurrence rates for block resection followed by bone graft are lower than those of enucleation and curettage. Follicular variants appear to recur more than plexiform variants. Unicystic tumors recur less frequently than "non-unicystic" tumors. Persistent follow-up examination is essential for managing ameloblastoma. Follow up should occur at regular intervals for at least 10 years. Follow up is important, because 50% of all recurrences occur within 5 years postoperatively. Recurrence within a bone graft (following resection of the original tumor) does occur, but is less common. Seeding to the bone graft is suspected as a cause of recurrence. The recurrences in these cases seem to stem from the soft tissues, especially the adjacent periosteum. Recurrence has been reported to occur as many as 36 years after treatment.

To reduce the likelihood of recurrence within grafted bone, meticulous surgery with attention to the adjacent soft tissues is required.

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.

There are many diagnostic methods that can be used to determine the type of salivary gland tumour and if it is benign or malignant. Examples of diagnostic methods include:

Physical exam and history: An exam of the body to check general signs of health. The head, neck, mouth, and throat will be checked for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken.

Endoscopy: A procedure to look at organs and tissues inside the body to check for abnormal areas. For salivary gland cancer, an endoscope is inserted into the mouth to look at the mouth, throat, and larynx. An endoscope is a thin, tube-like instrument with a light and a lens for viewing.

MRI

Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.

Fine needle aspiration (FNA) biopsy: The removal of tissue or fluid using a thin needle. An FNA is the most common type of biopsy used for salivary gland cancer, and has been shown to produce accurate results when differentiating between benign and malignant tumours.

Radiographs: An OPG (orthopantomogram) can be taken to rule out mandibular involvement. A chest radiograph may also be taken to rule out any secondary tumours.

Ultrasound: Ultrasound can be used to initially assess a tumour that is located superficially in either the submandibular or parotid gland. It can distinguish an intrinsic from an extrinsic neoplasm. Ultrasonic images of malignant tumours include ill defined margins.

The prognosis varies dramatically, depending on the type and stage at the time of treatment. However, the most common epitheliomas are very easily treated and rarely result in death.

Magnetic Resonance Imaging (MRI) scans provide an image of the soft tissues in the body using radio waves and strong magnets. MRI can be used instead of CT if the patient exhibits an allergy to the contrast media administered for the test. Sometimes prior to the MRI scan, an intravenous injection of a contrasting material called gadolinium is given to allow for a more detailed image. Patients on dialysis or those who have renal insufficiency should avoid this contrasting material as it may induce a rare, yet severe, side effect known as nephrogenic systemic fibrosis. A bone scan or brain imaging is not routinely performed unless signs or symptoms suggest potential metastatic involvement of these areas.

MRI scans should also be considered to evaluate tumour extension which has grown in major blood vessels, including the vena cava, in the abdomen. MRI can be used to observe the possible spread of cancer to the brain or spinal cord should the patient present symptoms that suggest this might be the case.

Treatment usually involves surgically removing the tumor and affected tissue. Also used cryosurgery and radiotherapy.

PUNLMPs are exophytic lesions that appear friable to the naked eye and when imaged during cystoscopy.

They are definitively diagnosed after removal by microscopic examination by pathologists.

Histologically, they have a papillary architecture with slender fibrovascular cores and rare basal mitoses. The papillae rarely fuse and uncommonly branch. Cytologically, they have uniform nuclear enlargement.

They cannot be reliably differentiated from low grade papillary urothelial carcinomas using cytology, and their diagnosis (vis-a-vis low grade papillary urothelial carcinoma) has a poor inter-rater reliability.

Pathologic grading and staging tumors are:

graded by the degree of cellular atypia (G1->G3), and

staged:

When associated with the prostate, squamous cell carcinoma is very aggressive in nature. It is difficult to detect as there is no increase in prostate specific antigen levels seen; meaning that the cancer is often diagnosed at an advanced stage.

Human papillomavirus infection (HPV) has been associated with SCC of the oropharynx, lung, fingers and anogenital region.

Prognosis can range considerably for patients, depending where on the scale they have been staged. Generally speaking, the earlier the cancer is diagnosed, the better the prognosis. The overall 5-year survival rate for all stages of penile cancer is about 50%.

PUNLMPs are treated like non-invasive low grade papillary urothelial carcinomas, excision and regular follow-up cystoscopies.

There is a rare occurrence of a pelvic recurrence of a low-grade superficial TCC after cystectomy. Delayed presentation with recurrent low-grade urothelial carcinoma is an unusual entity and potential mechanism of traumatic implantation should be considered. Characteristically low-grade tumors are resistant to systemic chemotherapy and curative-intent surgical resection of the tumor should be considered.

Radiologically

- Odontogenic Myxoma

- Ameloblastoma

- Central Giant Cell Granuloma

- Adenomatoid odontogenic tumor

Histologically

- Orthokeratocyst

- Radicular cyst (particularly if the OKC is very inflamed)

- Unicystic ameloblastoma