Discussion
Clinical forms of multiple KAs include Ferguson-Smith type, generalized eruptive Grzybowski type, centrifugum marginatum type, multiple persistent non-familial type, agglomerate type, KAs in Muir-Torre syndrome, and KAs in xeroderma pigmentosum (4).
KA of Ferguson-Smith type also known as multiple self-healing squamous epitheliomas (MSHSE) is the most common form of multiple KAs. It was first described in 1934 in Scottish families. However, sporadic cases have been reported in various countries (2,4).
Haplotypes for polymorphic markers segregating with Ferguson-Smith syndrome in non-Scottish and Scottish families differ, suggesting that Ferguson-Smith syndrome is not caused by a founder mutation, thus considered now as a digenic/multilocus disease (5,6) caused by loss of function mutations of Transforming growth factor, beta receptor I (TGFBR1) gene interacting with permissive variants at a second linked locus on the long arm of chromosome 9 (7). Inheritance is autosomal dominant with incomplete penetrance. De novo mutations are possible which may explain the absence of a family history of KA in our patient.
Multiple self-healing lesions usually appear during childhood, adolescence, or early adulthood. Men and women are equally affected. Although lesions may arise on any part of the skin, KAs are mainly located on the face and extremities. The trunk is rarely affected. Palms and soles are usually spared. Each lesion starts as a reddish macule, becomes papular, and then grows rapidly into an ordinary solitary KA. The number of KAs varies from a few to hundreds (4). They evolve and then disappear rapidly within months leaving atrophic and shallower scars and new KAs that keep continuously appearing.
Retinoids are the\sout-first-line treatment option for Ferguson-Smith syndrome (2). It is associated with a good clinical response. However, it has only a suspensive action. Therefore, a long-term regimen is necessary to sustain the clinical response. In our case, treatment with a relatively low dose of acitretin was efficient. Limited lesions can be treated with intralesional methotrexate (8). Cyclophosphamide was also used with good results in retinoid- and methotrexate-resistant cases of multiple KAs (9).