The decrease in hematopoietic tissue impairs the patients ability to generate new blood cells, resulting in progressive pancytopenia, a shortage of all blood cell types. However, the proliferation of fibroblasts and deposition of collagen is a secondary phenomenon, and the fibroblasts themselves are not part of the abnormal cell clone.In primary myelofibrosis, progressive scarring, or fibrosis, of the bone marrow occurs, for the reasons outlined above. The result is extramedullary hematopoiesis, i.e. blood cell formation occurring in sites other than the bone marrow, as the hemopoietic cells are forced to migrate to other areas, particularly the liver and spleen. This causes an enlargement of these organs. In the liver, the abnormal size is called hepatomegaly. Enlargement of the spleen is called splenomegaly, which also contributes to causing pancytopenia, particularly thrombocytopenia and anemia. Another complication of extramedullary hematopoiesis is poikilocytosis, or the presence of abnormally shaped red blood cells.Myelofibrosis can be a late complication of other myeloproliferative disorders, such as polycythemia vera, and less commonly, essential thrombocythemia. In these cases, myelofibrosis occurs as a result of somatic evolution of the abnormal hematopoietic stem cell clone that caused the original disorder. In some cases, the development of myelofibrosis following these disorders may be accelerated by the oral chemotherapy drug hydroxyurea.
A cystic hygroma is an abnormal growth that usually appears on a babys neck or head. It consists of one or more cysts and tends to grow larger over time. The disorder usually develops while the fetus is still in the uterus, but can also appear after birth.Also known as cystic lymphangioma and macrocystic lymphatic malformation, the growth is often a congenital lymphatic lesion of many small cavities (multiloculated) that can arise anywhere, but is classically found in the left posterior triangle of the neck and armpits. The malformation contains large cyst-like cavities containing lymph, a watery fluid that circulates throughout the lymphatic system. Microscopically, cystic hygroma consists of multiple locules filled with lymph. Deep locules are quite big, but they decrease in size towards the surface. Cystic hygromas are benign, but can be disfiguring. It is a condition which usually affects children; very rarely it can be present in adulthood.Currently, the medical field prefers to use the term lymphatic malformation, because the term cystic hygroma means water tumor. Lymphatic malformation is more commonly used now because it is a sponge-like collection of abnormal growth that contains clear lymphatic fluid. The fluid collects within the cysts or channels, usually in the soft tissue. Cystic hygromas occur when the lymphatic vessels that make up the lymphatic system are not formed properly. The two types of lymphatic malformations are macrocystic  (large cysts) and microcystic (small cysts) lymphatic malformations.