A lipoma is a benign tumor made of fat tissue. They are generally soft to the touch, movable, and painless. They usually occur just under the skin, but occasionally may be deeper. Most are less than 5 cm (2.0 in) in size. Common locations include upper back, shoulders, and abdomen. It is possible to have several lipomas.
Fibromas are benign tumors that are composed of fibrous or connective tissue. They can grow in all organs, arising from mesenchyme tissue. The term "fibroblastic" or "fibromatous" is used to describe tumors of the fibrous connective tissue. When the term fibroma is used without modifier, it is usually considered benign, with the term fibrosarcoma reserved for malignant tumors.
Dermatofibrosarcoma protuberans (DFSP) is a rare locally aggressive malignant cutaneous soft-tissue sarcoma. DFSP develops in the connective tissue cells in the middle layer of the skin (dermis). Estimates of the overall occurrence of DFSP in the United States are 0.8 to 4.5 cases per million persons per year. In the United States, DFSP accounts for between 1 and 6 percent of all soft-tissue sarcomas and 18 percent of all cutaneous soft-tissue sarcomas. In the Surveillance, Epidemiology and End Results (SEER) tumor registry from 1992 through 2004, DFSP was second only to Kaposi sarcoma.
Cherry angioma, also called cherry hemangioma or Campbell de Morgan Spot, is a small bright red dome-shaped bump on the skin. It ranges between 0.5 – 6 mm in diameter and usually several are present, typically on the chest and arms, and increasing in number with age. If scratched, they may bleed.
A seborrheic keratosis is a non-cancerous (benign) skin tumour that originates from cells, namely keratinocytes, in the outer layer of the skin called the epidermis. Like liver spots, seborrheic keratoses are seen more often as people age.
Fibrosarcoma is a malignant mesenchymal tumour derived from fibrous connective tissue and characterized by the presence of immature proliferating fibroblasts or undifferentiated anaplastic spindle cells in a storiform pattern. Fibrosarcomas mainly arise in people between the ages of 25 and 79. It originates in fibrous tissues of the bone and invades long or flat bones such as the femur, tibia, and mandible. It also involves the periosteum and overlying muscle.
In medicine, nodules are small firm lumps, usually greater than 1 cm in diameter. If filled with fluid they are referred to as cysts. Smaller raised soft tissue bumps may be termed papules.
Nodular fasciitis (NF) is a benign, soft tissue tumor composed of myofibroblasts that typically occurs in subcutaneous tissue, fascia, and/or muscles. The literature sometimes titles rare NF variants according to their tissue locations. The most frequently used and important of these are cranial fasciitis and intravascular fasciitis. In 2020, the World Health Organization classified nodular fasciitis as in the category of benign fibroblastic/myofibroblastic tumors. NF is the most common of the benign fibroblastic proliferative tumors of soft tissue.
A vascular tumor is a tumor of vascular origin; a soft tissue growth that can be either benign or malignant, formed from blood vessels or lymph vessels. Examples of vascular tumors include hemangiomas, lymphangiomas, hemangioendotheliomas, Kaposi's sarcomas, angiosarcomas, and hemangioblastomas. An angioma refers to any type of benign vascular tumor.
A blue nevus is a type of coloured mole, typically a single well-defined blue-black bump.
Giant cell fibroblastoma (GCF) is a rare type of soft-tissue tumor marked by painless nodules in the dermis and subcutaneous tissue. These tumors may come back after surgery, but they do not spread to other parts of the body. They occur mostly in boys. GCF tumor tissues consist of bland spindle-shaped or stellate-shaped cells interspersed among multinucleated giant cells.
Angiofibroma (AGF) is a descriptive term for a wide range of benign skin or mucous membrane lesions in which individuals have:
- benign papules, i.e. pinhead-sized elevations that lack visible evidence of containing fluid;
- nodules, i.e. small firm lumps usually >0.1 cm in diameter; and/or
- tumors, i.e. masses often regarded as ~0.8 cm or larger.
Glomangiosarcoma is a low grade tumor of the soft tissue. They rarely metastasize, but metastases are possible. It is also known as malignant glomus tumor. Positive staining for vimentin has been reported.
Aponeurotic fibroma, also known as calcifying aponeurotic fibroma, and juvenile aponeurotic fibroma is characterized by a lesion that usually presents as a painless, solitary, deep fibrous nodule, often adherent to tendon, fascia, or periosteum, on the hands and feet. The World Health Organization in 2020 reclassified aponeurotic fibroma nodules as a specific benign type of the fibroblastic and myofibroblastic tumors. Aponeurotic fibromas are diagnosed based off histopathology and treated by surgical excision. They are more common in males than females.
Infantile digital fibromatosis (IDF), also termed inclusion body fibromatosis, Reye tumor, or Reye's tumor, usually occurs as a single, small, asymptomatic, nodule in the dermis on a finger or toe of infants and young children. IMF is a rare disorder with approximately 200 cases reported in the medical literature as of 2021. The World Health Organization in 2020 classified these nodules as a specific benign tumor type in the category of fibroblastic and myofibroblastic tumors. IDF was first described by the Australian pathologist, Douglas Reye, in 1965.
Fibrous papule of the nose is a harmless small bump on or near the nose. It is typically dome-shaped, skin-colored, white or reddish, smooth and firm.Less frequently it can occur elsewhere on the face. Sometimes there are a few. It may be shiny and remains unchanged for life. There may be a central hair.
Targetoid hemosiderotic hemangioma, also known as a hobnail hemangioma is a skin condition characterized by a central brown or purplish papule that is surrounded by an ecchymotic halo. It may appear similar to melanoma. It was first described by Santa Cruz and Aronberg in 1988.
A superficial acral fibromyxoma is a type of myxoma and is a rare cutaneous condition characterized by a mesenchymal neoplasm that typically occurs on the digits of middle-aged adults.
Fibroblastic and myofibroblastic tumors (FMTs) develop from the mesenchymal stem cells which differentiate into fibroblasts and/or the myocytes/myoblasts that differentiate into muscle cells. FMTs are a heterogeneous group of soft tissue neoplasms. The World Health Organization (2020) defined tumors as being FMTs based on their morphology and, more importantly, newly discovered abnormalities in the expression levels of key gene products made by these tumors' neoplastic cells. Histopathologically, FMTs consist of neoplastic connective tissue cells which have differented into cells that have microscopic appearances resembling fibroblasts and/or myofibroblasts. The fibroblastic cells are characterized as spindle-shaped cells with inconspicuous nucleoli that express vimentin, an intracellular protein typically found in mesenchymal cells, and CD34, a cell surface membrane glycoprotein. Myofibroblastic cells are plumper with more abundant cytoplasm and more prominent nucleoli; they express smooth muscle marker proteins such as smooth muscle actins, desmin, and caldesmon. The World Health Organization further classified FMTs into four tumor forms based on their varying levels of aggressiveness: benign, intermediate, intermediate, and malignant.
Dermatofibrosarcoma protuberans, fibrosarcomatous (DFSP-FS), also termed fibrosarcomatous dermatofibrosarcoma protuberans, is a rare type of tumor located in the dermis. DFSP-FS tumors have been viewed as: 1) a more aggressive form of the dermatofibrosarcoma protuberans (DFSP) tumors because they have areas that resemble and tend to behave like malignant fibrosarcomas or 2) as a distinctly different tumor than DFSP. DFSP-FS tumors are related to DFSP. For example, surgically removed DFSP tumors often recur with newly developed fibrobosarcoma-like areas. Nonetheless, the World Health Organization (WHO), 2020, classified DFSP and DFSP-FS as different tumors with DFSP being in the category of benign and DFSP-FS in the category of rarely metastasizing fibroblastic and myofibroblastic tumors. This article follows the WHO classification: the 5-15% of DFSP tumors that have any areas of fibrosarcomatous microscopic histopathology are here considered DFSP-FS rather than DFSP tumors.
