Piebald trait: Autosomal dominant genetic developmental abnormality of pigmentation characterized by congenital patches of white skin and hair that lack melanocytes.
Gastrointestinal stromal tumor: Common mesenchymal neoplasms arising in the gastrointestinal tract, most often in the stomach. They are histologically, immunohistochemically, and genetically different from typical leiomyomas, leiomyosarcomas, and schwannomas. Most GISTs are composed of a fairly uniform population of spindle-shaped cells. Some tumors are dominated by epithelioid cells or contain a mixture of spindle and epithelioid morphologies. Primary GISTs in the gastrointestinal tract commonly metastasize in the omentum and mesenteries, often as multiple nodules. However, primary tumors may also occur outside of the gastrointestinal tract, in other intra-abdominal locations, especially in the omentum and mesentery.
Testicular germ cell tumor: A common malignancy in males representing 95% of all testicular neoplasms. TGCTs have various pathologic subtypes including: unclassified intratubular germ cell neoplasia, seminoma (including cases with syncytiotrophoblastic cells), spermatocytic seminoma, embryonal carcinoma, yolk sac tumor, choriocarcinoma, and teratoma.
Leukemia, acute myelogenous: A subtype of acute leukemia, a cancer of the white blood cells. AML is a malignant disease of bone marrow characterized by maturational arrest of hematopoietic precursors at an early stage of development. Clonal expansion of myeloid blasts occurs in bone marrow, blood, and other tissue. Myelogenous leukemias develop from changes in cells that normally produce neutrophils, basophils, eosinophils and monocytes.
Mastocytosis, cutaneous: A form of mastocytosis, a heterogeneous group of disorders associated with abnormal proliferation and accumulation of mast cells in various tissues, especially in the skin and hematopoietic organs. MASTC is an autosomal dominant form characterized by macules, papules, nodules, or diffuse infiltration of the skin, often associated with localized hyperpigmentation. Gentle rubbing of the lesions induces histamine release from mechanically activated mast cells, causing local wheals, erythema, and often pruritus, a phenomenon termed Darier sign.
Mastocytosis, systemic: A severe form of mastocytosis characterized by abnormal proliferation and accumulation of mast cells in several organs, resulting in a systemic disease that may affect bone, gastrointestinal tract, lymphatics, spleen, and liver. In some cases, it is associated with a clonal hematologic non-mast-cell lineage disease, such as a myelodysplastic or myeloproliferative disorder. It can also lead to mast cell leukemia, which carries a high risk of mortality.
