Skin lesions due to abnormal infiltration of MAST CELLS. Cutaneous mastocytosis is confined to the skin without the involvement of other tissues or organs, and is mostly found in children. The three major variants are: URTICARIA PIGMENTOSA; diffuse cutaneous mastocytosis; and SOLITARY MASTOCYTOMA OF SKIN.

The most common form of cutaneous mastocytosis (MASTOCYTOSIS, CUTANEOUS) that occurs primarily in children. It is characterized by the multiple small reddish-brown pigmented pruritic macules and papules.

A heterogenous group of disorders characterized by the abnormal increase of MAST CELLS in only the skin (MASTOCYTOSIS, CUTANEOUS), in extracutaneous tissues involving multiple organs (MASTOCYTOSIS, SYSTEMIC), or in solid tumors (MASTOCYTOMA).

A unifocal malignant tumor that consists of atypical pathological MAST CELLS without systemic involvement. It causes local destructive growth in organs other than in skin or bone marrow.

Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the BASOPHILS, mast cells contain large amounts of HISTAMINE and HEPARIN. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the STEM CELL FACTOR.

A sarcoma of young, often female, adults of the lower extremities and acral regions, intimately bound to tendons as circumscribed but unencapsulated melanin-bearing tumors of neuroectodermal origin. An ultrastructural finding simulates flattened and curved barrel staves, corresponding to the internal structures of premelanosomes. There is a 45-60% mortality in clear cell sarcoma. (Segen, Dictionary of Modern Medicine, 1992)

A group of disorders caused by the abnormal proliferation of MAST CELLS in a variety of extracutaneous tissues including bone marrow, liver, spleen, lymph nodes, and gastrointestinal tract. Systemic mastocytosis is commonly seen in adults. These diseases are categorized on the basis of clinical features, pathologic findings, and prognosis.

Rare malignant neoplasm of dendritic LANGERHANS CELLS exhibiting atypical cytology, frequent mitoses, and aggressive clinical behavior. They can be distinguished from other histiocytic and dendritic proliferations by immunohistochemical and ultrastructure studies. Cytologically benign proliferations of Langerhans cells are called LANGERHANS CELL HISTIOCYTOSIS.

A connective tissue neoplasm formed by proliferation of mesodermal cells; it is usually highly malignant.

Sarcoma of FOLLICULAR DENDRITIC CELLS most often found in the lymph nodes. This rare neoplasm occurs predominately in adults.

A sarcoma characterized by the presence of small cells, cells measuring 9-14 micrometers with a faint or indistinct rim of cytoplasm and an oval-to-elongated nucleus with relatively dense chromatin. (From Segen, Dictionary of Modern Medicine, 1992)

A rare sarcoma of INTERDIGITATING CELLS found in the lymph nodes and non-lymphoid organs. They exhibit a variable immunophenotype and lack Birbeck granules.

A family of neutral serine proteases with TRYPSIN-like activity. Tryptases are primarily found in the SECRETORY GRANULES of MAST CELLS and are released during mast cell degranulation.