Calcinosis cutis in porphyria cutanea tarda – not always a marker of disease activity

ARTICLE

Auteur(s) : Ana Nogueira, Elisabete Moreira, Paulo Santos, Filomena Azevedo

Department of Dermatology and Venereology, Hospital S. João, EPE, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal

Porphyria cutanea tarda (PCT) is the most common type of porphyria and results from the deficient activity of uroporphyrinogen decarboxilase [1]. Cutaneous calcification in the setting of this disease is a very rare occurrence, with few reports in the literature, most of them in older publications. It is a phenomenon that is still poorly understood, although it is clearly a dystrophic event [2-5]. We report dystrophic calcification of the scalp in a patient with PCT.

A 72-year-old man was sent for dermatological consultation in 2006 because of hard nodular lesions of the scalp. These lesions had been appearing for several years and were asymptomatic. He reported a past medical history of PCT, manifested by skin fragility with blisters on the dorsum of the hands, scalp and neck between 1974 and 2003. Investigations carried out in 1991 revealed: normal hemogram, slightly increased bilirubinemia (1.38 mg/dL, normal below 1.1 mg/dL), ALT 45 UI/L (normal 10-37 IU/I), G-GT 100 (normal 10-49 IU/L), iron 188 μg/dL (normal 80-160 μg/dL), total porphyrins in the urine of 3224 μg/24h (normal up to 220), uroporphyrin 2312 μg/24h (normal up to 60), coproporphyrin 913 μg/24h (normal up to 160). He had undergone several phlebotomies between 2002 and 2004, achieving both clinical and biochemical control of the disease.

Currently we observed alopecia, with post-inflammatory depigmented areas, along with nodular lesions in the supra, retro-auricular areas and vertex with slightly inflammatory borders and transepidermal elimination of a chalky whitish material in the centre. The supra auricular region had an indurated and infiltrated consistence, with a scleroderma-like appearance (figure 1A, B). The patient also displayed hypopigmentation on the dorsum of the hands. No nodular lesions were found elsewhere in the body.

The diagnosis of calcification in the scenario of PCT was clinically apparent, and curettage of the larger lesion was performed both for cosmetic improvement and histological confirmation. The biopsy showed several fragments of calcific material within a fibrotic dermis (figure 1C). The skull X-ray disclosed numerous foci of calcification on the scalp and also on the neck (figure 1D). A complete laboratory workup revealed: normal immunological study, normal phosphorus-calcium metabolism, normal PTH and vitamin D, normal iron metabolism, normal hemogram, and slightly impaired hepatic function (AST 42, ALT 43, normal 10-37 IU/L; G-GT 159, normal 10-49 IU/L; AP 78, normal 44-155 IU/L; total bilirubin 1.13, normal up to 1.1 mg/dL). Serologies for HIV and hepatitis, including hepatitis C virus, were negative. The most common HFE gene mutations for hemochromatosis were negative, namely C282Y, H63D and S65C.

Interestingly, the porphyrins in the urine were normal, which means that dystrophic calcification continued to occur despite normalization of the disease activity. This observation contrasts to previous descriptions, with most, if not all, reports of calcification occurring in patients with long lasting untreated PCT [2-4].

It has been considered that local tissue disruption by repeated cycles of skin inflammation and blistering is the main initiation event for calcification in PCT. High iron levels may also contribute to this, as iron deposits impart collagen fibres with a higher affinity for calcium [4]. However, there have been reports of calcinosis with normal iron levels, as in our case. This phenomenon mostly occurs in the pre-auricular region, scalp, neck and dorsum of the hands, and is frequently associated with scleroderma-like lesions. It can also take place in elbows and knees, limiting movement [3]. It gives rise to plaques that frequently undergo central ulceration and may resolve with transepidermal elimination of the fragments [4, 5]. Phlebotomies are rarely helpful at this stage, and resection of the lesions with subsequent skin grafting is sometimes required [2].

In our case, we decided not to treat the other skin lesions at this time, as they were relatively asymptomatic. He is however, under regular follow-up.

Acknowledgments

References

2 Rey J, Hesse S, Bonerandi JJ. Extensive calcification of the scalp in a patient with porphyria cutanea tarda secondary to hepatitis C virus infection. JEADV 2007; 21: 286-7.

3 Gianadda B, Gianadda E, Leonetti F, Topi GC. Calcifications in porphyria cutanea tarda sclerodermiforme (Article in French). Ann Dermatol Venereol 1982; 109: 75-8.

4 Strumia R, Bettoli V, Marchetti F. Cutaneus calcinosis with transepithelial elimination in porphyria cutanea tarda. Chemico-structural characterization (Article in Italian). G Ital Dermatol Venereol 1990; 125: 201-4.

5 Walsh JS, Fairley JA. Calcifying disorders of the skin. J Am Acad Dermatol 1995; 33: 693-706.