Case report; A rare evolving disorder of multiple lesions with an elusive diagnosis

A 37-year-old female presented with a non-specific annular indurated flesh-coloured lesion on the right side of her neck. She also presented 12 months later with a similar but larger lesion on her back. Past history included a basal cell carcinoma excised from the right temple at age 35, and a lesion on the dorsum of the right hand which had enlarged gradually over several years when she was an adolescent. Physical examination showed a lesion over the left scapula (Fig. 1). The lesion had visible central atrophy with a slightly raised indurated rim. The depressed area centrally measured 2 × 2 cm. Histology from an incisional biopsy of the back lesion demonstrated mild epidermal atrophy with underlying papillary dermal fibrosis. There was mild perivascular inflammatory cell infiltrate composed predominantly of lymphocytes. Elastin van Gieson (EVG) staining demonstrated fragmentation of the elastic fibres in the dermis (Fig. 2). Given the clinical presentation and histopathology, a diagnosis of Annular atrophic plaques of the skin, also known as Christianson's disease was made. Christianson's disease is very rare, and little reported in the literature1-6. Currently only one case2 is reported in women. As seen in our patient, the plaques are thought to predominantly occur on sun-exposed skin, are asymptomatic and evolve in size.1,3-6 Classically, the lesions have atrophic centres with a white thickened border which becomes sclerotic with time1-6. In support of our diagnosis, our patient's histology showed peri-adnexal inflammation of the dermis with a lymphocytic infiltration and overlying atrophied epidermis, similar to prior cases.1,4,5 Retrospective EVG staining from previous histology of the neck also demonstrated elastin fibre fragmentation, further supporting our diagnosis. There is much dilemma as to whether the plaques are a form of discoid lupus erythematosus (DLE)1-3, morphoea1 or lichen sclerosis1 or represent a unique disorder.4 Differentials such as lichen sclerosis and morphoea were less likely in our case taking in to consideration both the clinical presentation and histology demonstrating fragmentation of elastic fibres. Sharma et al. suggest the plaques could be an end stage of the skin disorders listed above.5 This process is also true for other types of anetoderma such as Jadassohn-Pellizzari type and Schweninger-Buzzi type. Interestingly, anetoderma has a similar process whereby there is atrophy and loss of dermal elastic fibres.7 This in fact may qualify Christianson's disease as an anetoderma. Histology from previous cases of anetoderma have also found histology to demonstrate perivascular infiltrate composed of lymphocytes.7 Furthermore, Pietsch et al.6, also suggest an underlying genetic component to the condition which has not previously considered. Christianson's disease is a rare and complex dermatological disease, resulting in limited literature coverage. Our case describes Christianson's disease in a woman, only documented once before.2 The challenges posed by limited coverage include varying histological findings and it has unclear association with other conditions. To address these unanswered questions, it's important to uncover more cases with longer follow-up and biopsies of fresh and older lesions.