It presents as a slow growing mass that especially affects tendons and aponeuroses and it is deeply situated. Patients often perceive it as a lump or hard mass. It causes either pain or tenderness but only until it becomes large enough. This kind of tumor is commonly found in the extremities especially around the knee, feet and ankle. Patients diagnosed with clear cell sarcoma are usually between the ages of 20 and 40.

Individuals presenting with fibrosarcoma are usually adults aged thirty to fifty five years, often presenting with pain. In adults, males have a higher incidence for fibrosarcoma than females.

Ancillary testing for fibrosarcoma includes IHC, where vimentin is positive, cytokeratin and S100 are negative, and actin is variable.

Patients usually present with pain and limited range of motion caused by tumor's proximity to the joint space. Swelling may occur, as well, if the tumor has been growing for a long time. Some patients may be asymptomatic until they develop a pathologic fracture at the site of the tumor. They usually originate from the epiphysis of long bones, but in rare cases, they may arise from anterior arc of the ribs.

The symptoms may include muscular aches and pains in arms or legs and abdominal pain. Patients may also experience nerve pain which feels like an electric shock due to weight bearing.

Sarcomatoid carcinoma is a relatively uncommon form of cancer whose malignant cells have histological, cytological, or molecular properties of both epithelial tumors ("carcinoma") and mesenchymal tumors ("sarcoma").

Histological variants of lung cancer classified as sarcomatoid carcinoma include pleomorphic carcinoma, giant cell carcinoma, spindle cell carcinoma, carcinosarcoma, and pulmonary blastoma.

When the tumor is large and there is presence of necrosis and local recurrence, the prognosis is poor. Presence of metastasis occurs in more than 50% cases and the common places of its occurrence are the bone, lymph node and lungs. Five-year survival rates, which are reported to be between 50-65%, can be misleading because the disease is prone to late metastasis or recurrence. Ten and twenty-year survival rates are 33% and 10%, respectively.

Keratoacanthomas (molluscum sebaceum) may be divided into the following types:

- "Giant keratoacanthomas" are a variant of keratoacanthoma, which may reach dimensions of several centimeters.

- "Keratoacanthoma centrifugum marginatum" is a cutaneous condition, a variant of keratoacanthomas, which is characterized by multiple tumors growing in a localized area.

- "Multiple keratoacanthomas" (also known as "Ferguson–Smith syndrome," "Ferguson-Smith type of multiple self-healing keratoacanthomas,") is a cutaneous condition, a variant of keratoacanthomas, which is characterized by the appearance of multiple, sometimes hundreds of keratoacanthomas.

- A "solitary keratoacanthoma" (also known as "Subungual keratoacanthoma") is a benign, but rapidly growing, locally aggressive tumor which sometimes occur in the nail apparatus.

- "Generalized eruptive keratoacanthoma" (also known as "Generalized eruptive keratoacanthoma of Grzybowski") is a cutaneous condition, a variant of keratoacanthomas, characterized by hundreds to thousands of tiny follicular keratotic papules over the entire body. Treatments are not successful for many patients with Generalized eruptive keratoacanthoma. Use of emollients and anti-itch medications can ease some symptoms. Improvement or complete resolutions of the condition has occurred with the application of the following medications: Acitretin, Isotretinoin, Fluorouracil, Methotrexate, Cyclophosphamide.

Giant-cell tumor of the bone (GCTOB) is a relatively uncommon tumor of the bone. It is characterized by the presence of multinucleated giant cells (osteoclast-like cells). Malignancy in giant-cell tumor is uncommon and occurs in about 2% of all cases. However, if malignant degeneration does occur, it is likely to metastasize to the lungs. Giant-cell tumors are normally benign, with unpredictable behavior. It is a heterogeneous tumor composed of three different cell populations. The giant-cell tumour stromal cells (GCTSC) constitute the neoplastic cells, which are from an osteoblastic origin and are classified based on expression of osteoblast cell markers such as alkaline phosphatase and osteocalcin. In contrast, the mononuclear histiocytic cells (MNHC) and multinucleated giant cell (MNGC) fractions are secondarily recruited and comprise the non-neoplastic cell population. They are derived from an osteoclast-monocyte lineage determined primarily by expression of "CD68", a marker for monocytic precursor cells. In most patients, the tumors are slow to develop, but may recur locally in as many as 50% of cases.

Keratoacanthoma (KA) is a common low-grade (unlikely to metastasize or invade) skin tumour that is believed to originate from the neck of the hair follicle.

The defining characteristic of KA is that it is dome-shaped, symmetrical, surrounded by a smooth wall of inflamed skin, and capped with keratin scales and debris. It grows rapidly, reaching a large size within days or weeks, and if untreated for months will almost always starve itself of nourishment, necrose (die), slough, and heal with scarring. KA is commonly found on sun-exposed skin, often face, forearms and hands.

Under the microscope, keratoacanthoma very closely resembles squamous cell carcinoma. In order to differentiate between the two, almost the entire structure needs to be removed and examined. While some pathologists classify KA as a distinct entity and not a malignancy, about 6% of clinical and histological keratoacanthomas do progress to invasive and aggressive squamous cell cancers; some pathologists may label KA as "well-differentiated squamous cell carcinoma, keratoacanthoma variant", and prompt definitive surgery may be recommended.

Giant-cell carcinoma of the lung (GCCL) is a rare histological form of large-cell lung carcinoma, a subtype of undifferentiated lung cancer, traditionally classified within the non-small-cell lung carcinomas (NSCLC).

The characteristic feature of this highly lethal malignancy is the distinctive light microscopic appearance of its extremely large cells, which are bizarre and highly pleomorphic, and which often contain more than one huge, misshapen, pleomorphic nucleus ("syncytia"), which result from cell fusion.

Although it is common in the lung cancer literature to refer to histologically mixed tumors containing significant numbers of malignant giant cells as "giant-cell carcinomas", technically a diagnosis of "giant-cell carcinoma" should be limited strictly to neoplasms containing "only" malignant giant cells (i.e. "pure" giant-cell carcinoma).

Aside from the great heterogeneity seen in lung cancers (especially those occurring among tobacco smokers), the considerable variability in diagnostic and sampling techniques used in medical practice, the high relative proportion of individuals with suspected GCCL who do not undergo complete surgical resection, and the near-universal lack of complete sectioning and pathological examination of resected tumor specimens prevent high levels of quantitative accuracy.

Malignant transformation to squamous cell carcinoma may occur, but is unusual.

Patients typically present with a non-productive cough and weight loss.

Giant-cell fibroblastoma is a rare type of soft-tissue tumor marked by painless nodules in the dermis (the inner layer of the two main layers of tissue that make up the skin) and subcutaneous (beneath the skin) tissue. These tumors may come back after surgery, but they do not spread to other parts of the body. They occur mostly in boys and are related to dermatofibrosarcoma protuberans.

Carcinoma is a type of cancer that develops from epithelial cells. Specifically, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that arises from cells originating in the endodermal, mesodermal and ectodermal germ layer during embryogenesis.

Carcinomas occur when the DNA of a cell is damaged or altered and the cell begins to grow uncontrollably and become malignant. It is from the Greek καρκίνωμα 'karkinoma' meaning sore, ulcer, or cancer, itself derived from "karkinos" 'crab'.

Pilomatricoma, also known as a calcifying epithelioma of Malherbe, Malherbe calcifying epithelioma, and Pilomatrixoma, is a benign skin tumor derived from the hair matrix. These neoplasms are relatively uncommon and typically occur on the scalp, face, and upper extremities. Clinically, pilomatricomas present as a subcutaneous nodule or cyst with unremarkable overlying epidermis that can range in size from 0.5-3.0 cm, but the largest reported case was 24 cm.

Swelling is the most common presenting complaint; however, OKCs may be asymptomatic and found incidentally on dental X-rays.

Bowen's disease typically presents as a gradually enlarging, well-demarcated red colored plaque with an irregular border and surface crusting or scaling. Bowen's disease may occur at any age in adults, but is rare before the age of 30 years; most patients are aged over 60. Any site may be affected, although involvement of palms or soles is uncommon. Bowen's disease occurs predominantly in women (70–85% of cases). About 60–85% of patients have lesions on the lower leg, usually in previously or presently sun-exposed areas of skin.

This is a persistent, progressive, unelevated, red, scaly or crusted plaque which is due to an intraepidermal carcinoma and is potentially malignant. The lesions may occur anywhere on the skin surface, including on mucosal surfaces. Freezing, cauterization, or diathermy coagulation is often effective treatment. Pathomorphologic study of tissue sampling revealed: polymorphism of spiny epithelial cells has progressed into atypism; increased mitosis; giant and multinucleate cells; acanthosis; hyperkeratosis and parakeratosis; basal membrane and basal layer are retained.

Large-cell carcinoma (LCC) is a heterogeneous group of undifferentiated malignant neoplasms that lack the cytologic and architectural features of small cell carcinoma and glandular or squamous differentiation. LCC is categorized as a type of NSCLC (Non-Small Cell Carcinoma) which originates from epithelial cells of the lung.

Giant-cell fibroma is a type of fibroma not associated with trauma or irritation. It can occur at any age and on a mucous membrane surface. The most common oral locations are on the gingiva of the mandible, tongue, and palate. It is a localized reactive proliferation of fibrous connective tissue.

Giant-cell fibroma (GCF) is a benign non-neoplastic lesion first described by Weathers and Callihan (1974). It occurs in the first three decades of life and predominates in females (Houston, 1982; Bakos, 1992). Clinically, the GCF presents as an asymptomatic, papillary and pedunculated lesion. The most predominant location is the mandibular gingiva (Houston, 1982; Bakos, 1992). Histologically, the GCF is distinctive, consisting of fibrous connective tissue without inflammation and covered with stratified squamous hyperplastic epithelium. The most characteristic histological feature is the presence of large spindle-shaped and stellate-shaped mononuclear cells and multinucleated cells. These cells occur in a variety of lesions, such as the fibrous papule of the nose, ungual fibroma, acral fibrokeratoma, acral angiofibroma and desmoplastic fibroblastoma (Swan, 1988; Pitt et al., 1993; Karabela-Bouropoulou et al., 1999; Jang et al., 1999).

Despite many studies, the nature of the stellated multinucleate and mononuclear cell is not clear (Weathers and Campbell, 1974; Regezi et al., 1987; Odell et al., 1994; Magnusson and Rasmusson, 1995).

Bowen's disease, also known as squamous cell carcinoma" in situ" is a neoplastic skin disease. It can be considered as an early stage or intraepidermal form of squamous cell carcinoma. It was named after John T. Bowen.

Erythroplasia of Queyrat is a particular type of Bowen's disease that can arise on the glans or prepuce in males, and, on the vulva in females, and may be induced by human papilloma virus. It is reported to occur in the corneoscleral limbus.

CGCG lesions are found more commonly in the anterior of the maxilla and the mandible in younger people (before age 20). They are characterized by large lesions that expand the cortical plate and can resorb roots and move teeth. They are composed of multi-nucleated giant cells. CGCG has a slight predilection for females.

Radiographically :

It appears as multilocular radiolucencies of bone.The margin of the lesion has scalloped appearance and is well demarcated. Resorption and divergence of roots is also seen.

There are two types of CGCG's, non-aggressive and aggressive. The former has a slow rate of growth and thus less likely to resorb roots and perforate the cortical plate. The aggressive form has rapid growth and thus is much more likely to resorb roots and perforate the cortical plate. It also has a high rate for recurrence and can be painful and cause paresthesia.

Differential diagnosis to include: odontogenic keratocyst (OKC), ameloblastoma, odontogenic myxoma, hemangioma, central odontogenic fibroma, hyperparathyroid tumor, and cherubism.

For several decades, primary lung cancers were consistently dichotomously classified for treatment and research purposes into small-cell lung carcinomas (SCLCs) and non-small-cell lung carcinomas (NSCLCs), based on an oversimplified approach that is now clearly outmoded. The new paradigm recognizes that lung cancers are a large and extremely heterogeneous family of malignant neoplasms, with over 50 different histological variants included in the 4th (2004) revision of the World Health Organization typing system, the most widely used lung cancer classification scheme ("WHO-2004"). These variants are increasingly appreciated as having different genetic, biological, and clinical properties, including prognoses and responses to treatment regimens, and therefore, that correct and consistent histological classification of lung cancers are necessary to validate and implement optimum management strategies.

About 1% of lung cancers are sarcomas, germ cell tumors, and hematopoietic tumors, while 99% of lung cancers are carcinoma. Carcinomas are tumors composed of transformed, abnormal cells with epithelial tissue architecture and/or molecular characteristics, and which derive from embryonic endoderm. Eight major taxa of lung carcinomas are recognized within the WHO-2004 classification:

1. Small-cell carcinoma

2. Squamous cell carcinoma

3. Adenocarcinoma

4. Large-cell carcinoma

5. Adenosquamous carcinoma

6. Sarcomatoid carcinoma

7. Carcinoid

8. Salivary gland-like carcinoma

The subclassification of GCCL among these major taxa has undergone significant changes in recent decades. Under the 2nd revision (1981) of the WHO classification, it was considered a subtype of large-cell carcinoma. In the 3rd (1999) revision, it was placed within a taxon called "Carcinomas with Pleomorphic, Sarcomatoid, or Sarcomatous Elements", along with pleomorphic carcinoma, spindle cell carcinoma, carcinosarcoma, and pulmonary blastoma, which are (arguably) related variants. While the 4th revision ("WHO-2004") retained the same grouping of lesions as the 3rd revision, the name of the major taxon was shortened to "sarcomatoid carcinomas".

The current rules for classifying lung cancers under WHO-2004, while useful and improved, remain to some extent fairly complex, ambiguous, arbitrary, and incomplete. Although it is fairly common for mixed tumors that are seen to contain malignant giant cells to be called "giant-cell carcinomas", "accurate" classification of a pulmonary tumor as a GCCL requires that the "entire tumor" consists "only" of malignant giant cells. Therefore, complete sampling of the entire tumor — obtained via a surgical resection — is absolutely necessary for a definitive diagnosis of GCCL to be made.

There are many subtypes of lipomas:

- Adenolipomas are lipomas associated with eccrine sweat glands.

- Angiolipoleiomyomas are acquired, solitary, asymptomatic nodules, characterized histologically by well-circumscribed subcutaneous tumors composed of smooth muscle cells, blood vessels, connective tissue, and fat.

- Angiolipomas are painful subcutaneous nodules having all other features of a typical lipoma.

- Cerebellar pontine angle and internal auditory canal lipomas

- Chondroid lipomas are deep-seated, firm, yellow tumors that characteristically occur on the legs of women.

- Corpus callosum lipoma is a rare congenital brain condition that may or may not present with symptoms. This occurs in the corpus callosum, also known as the calossal commissure, which is a wide, flat bundle of neural fibers beneath the cortex in the human brain.

- Hibernomas are lipomas of brown fat.

- Intradermal spindle cell lipomas are distinct in that they most commonly affect women and have a wide distribution, occurring with relatively equal frequency on the head and neck, trunk, and upper and lower extremities.

- Neural fibrolipomas are overgrowths of fibro-fatty tissue along a nerve trunk, which often leads to nerve compression.

- Pleomorphic lipomas, like spindle-cell lipomas, occur for the most part on the backs and necks of elderly men and are characterized by floret giant cells with overlapping nuclei.

- Spindle-cell lipomas are asymptomatic, slow-growing subcutaneous tumors that have a predilection for the posterior back, neck, and shoulders of older men.

- Superficial subcutaneous lipomas, the most common type of lipoma, lie just below the surface of the skin. Most occur on the trunk, thigh, and forearm, although they may be found anywhere in the body where fat is located.

As of 2004, no simple and comprehensive classification system has been devised and accepted within the scientific community. Traditionally, however, malignancies have generally been classified into various types using a combination of criteria, including:

the cell type from which they start, specifically:

1. Epithelial cells ⇨ carcinoma

2. Non-hematopoietic mesenchymal cells ⇨ sarcoma

3. Hematopoietic cells

1. bone marrow-derived cells that normally mature in the bloodstream ⇨ Leukemia

2. bone marrow-derived cells that normally mature in the lymphatic system ⇨ Lymphoma

4. Germ cells ⇨ Germinoma

Other criteria that play a role in a cancer diagnosis include:

- The degree to which the malignant cells resemble their normal, untransformed counterparts

- the appearance of the local tissue and stromal architecture

- the anatomical location from which tumors arise

- genetic, epigenetic, and molecular features