What is the fine-grained topic of the following text: Smooth muscle hamartomas display a distinctive histopathology as do leiomyomas (which may show increased firmness with manual stroking of the site [pseudo-Darier sign]); pseudoxanthoma elasticum (which can mimic especially Buschke-Ollendorf syndrome) with characteristic location of papules, absence of bone findings, vascular disease, especially affecting Retina/GI tract/heart; and sclerotic fibromas associated with Cowden syndrome. Only return the topic.
Distinctive histopathology of various skin conditions and diseases