Unsafe deposits: Overlapping cutaneous manifestations of porphyria cutanea tarda, ochronosis, hemochromatosis, and argyria

Cutaneous deposition disorders represent an array of conditions resulting from the accumulation of endogenous and exogenous substances within the skin. Many of the deposition diseases resemble each other and can also be confused with disorders not related to deposition. Porphyria cutanea tarda (PCT) results from dysfunction particularly in the fifth enzyme of the heme synthesis pathway, leading to increased skin fragility and bullae among other abnormalities. Ochronosis develops from alkaptonuria or exogenous sources, creating deposition of ocher-colored pigment in the skin. Hemochromatosis is a systemic disorder that can be inherited or acquired, altering skin pigmentation in more than 90% of patients. PCT can be an initial manifestation of hemochromatosis. Argyria is an acquired disorder of silver deposition that can also cause pigmentation similar to ochronosis. These uncommon but not rare disorders may resemble and be confused with each other in multiple ways.