Epidermal thickening is another characteristic histologic finding of psoriasis lesions. Chondromyxoid fibromas can share characteristics with chondroblastomas with regards to histologic and radiographic findings. It is an epithelial malignancy characterized by the histologic appearance of signet ring cells. Biopsy of skin may be done to assess the histologic characteristics of the cells. In heavily pigmented lesions, dense aggregates of melanin can obscure histologic detail. This accounts for the histologic variants seen on biopsy. Patients do not usually have symptomatic or histologic respiratory involvement. Dilated submucosal veins are the most prominent histologic feature of esophageal varices. The diagnosis of TEN is based on both clinical and histologic findings. This is dependent on several histologic features within the abnormal parathyroid gland itself. Inverted papillomas are definitively diagnosed by histologic examination. The clinical and histologic features of oral lichenoid contact reactions are similar to oral LP. The histologic appearance is similar to oral leukoplakia, with hyperkeratosis and acanthosis. The histologic findings of these disorders are also similar. Chorioamnionitis can be diagnosed from a histologic examination of the fetal membranes.