Causes
Gestational choriocarcinoma (GC) is the most aggressive form of trophoblastic tumor; it most commonly arises from certain fertilization defects, such as molar pregnancy, which results in increased level of growth factors and uncontrolled proliferation of trophoblasts in the uterus. Statistics from clinical cases have shown that GC is associated with any pregnancy events, with 50% of GC arise from hydatidiform moles, 25% from gestation, and 25% from abortion or tubal pregnancy. Risk factors
The exact underlying causes for this disease are still not fully elucidated, part of the reasons being that this condition is very rare and it is clinically hard to distinguish it from invasive mole, which are other type of trophoblastic tumor  that present some similarities as GC. But several risk factors have been reported to have association with gestational choriocarcinoma. Maternal age. This is one of the two well-established risk factors for GC. Many studies have shown that the risk of developing GC increased very rapidly in gestational women older than 40 years old. Prior history of complete hydatidiform mole. This is another well-established risk factor for GC. It has been showed that the risk of having GC after a complete hydatidiform mole is significantly higher than after a live birth. Others risk factors such as reproductive factors, use of oral contraceptives, diet and environmental factors were also reported. But because of data inconsistency, such associations are still questionable. For example, there is a case-control study showed that theres a significant association of GC in women having more than 5 births.
Trichoepithelioma is a neoplasm of the adnexa of the skin. Its appearance is similar to basal cell carcinoma. One form has been mapped to chromosome 9p21. Types
Trichoepitheliomas may be divided into the following types:: 672 
Multiple familial trichoepithelioma
Solitary trichoepithelioma
Desmoplastic trichoepithelioma

Pathology
Trichoepitheliomas consists of nests of basaloid cells, with palisading. They lack the myxoid stroma and artefactual clefting seen in basal cell carcinoma. Mitoses are uncommon when compared to basal cell carcinoma. Diagnosis
Trichoepiteliomas often contain Merkel cells; an immunostain for CK20 can be used to demonstrate this. See also
Trichoblastoma
Pilomatricoma
CYLD cutaneous syndrome
List of cutaneous conditions
List of cutaneous neoplasms associated with systemic syndromes

References


== External links ==