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).