Milium cysts on hands; hypertrichosis on face
The patient’s dermatologic symptoms and his history of a particular chronic condition pointed toward the diagnosis.
Dermatologic manifestations of PCT include photosensitivity, skin fragility, vesicles, bullae, erosions, and crusts observed in sun-exposed areas. A nonvirilizing type of hypertrichosis may appear prominently on the temples and the cheeks.2-4 After blisters rupture, atrophy and scarring occur. Milia cysts can form on the dorsal side of the hands and fingers. Less common manifestations include pruritus, scarring alopecia, sclerodermatous changes, and periorbital purple-red suffusion.
Hepatic involvement is demonstrated with elevated serum transaminases and gamma-glutamyl transpeptidase. Hepatomegaly is common, and cirrhosis manifests in 30% to 40% of patients.2-5 On liver biopsy, some degree of siderosis is found in 80% of patients with PCT, and most of them have increased levels of serum iron. The incidence of hepatocellular carcinoma in patients with PCT is greater than in patients with other liver diseases.2
A Wood lamp can be a useful diagnostic first step
Plasma or urine porphyrin lab tests are the gold standard for PCT diagnosis. These tests can be followed by more specific tests (eg, porphyrin fractionation) to exclude other forms of porphyria. However, if plasma or urine porphyrin testing is not readily available, a good first step is a Wood lamp exam, which can be performed on urine or stool. (Plasma or urine porphyrin testing may ultimately be necessary if there is doubt about the diagnosis following the Wood lamp screening.) Histopathologic examination does not confirm the diagnosis of PCT4; however, it can be helpful in differential diagnosis.
Wood lamp is a source of long-wave UV light (320 to 400 nm), visualized as a purple or violet light. When porphyrins are present in a urine sample, a red-pink fluorescence may be seen.3,4,6 The Wood lamp examination should be performed in a completely dark room after the lamp has been warmed up for about 1 minute; time should be allowed for the clinician’s vision to adapt to the dark.6 There are no data regarding the sensitivity or specificity of the Wood lamp test in the diagnosis of PCT.
These conditions also cause skin fragility and photosensitivity
The differential diagnosis for PCT includes diseases that also cause skin fragility, blistering, or photosensitivity, such as pseudoporphyria, bullous systemic lupus erythematosus (SLE), and epidermolysis bullosa acquisita (EBA).3
Continue to: In pseudoporphyria
