Discussion
DDD is a rare autosomal dominant genodermatosis but can also occur
sporadically. It is characterized by asymptomatic, progressive,
reticulate hyperpigmented macules with a flexural distribution. Other
cutaneous findings include comedo-like hyperkeratotic follicular papules
on the neck, perioral pitted acneiform scars.5Loss-of-functional mutation in the keratin 5 (KRT5) gene on chromosome
12q13 is reported. Mutation of the gene results in disruption in
melanosome transfer and trafficking. Gene locus mapping to chromosome
17p13.3 has also been reported. Other genes involved in pathogenesis of
DDD are POGLUT1(protein O-glucosyltransferase 1) ,POFUT1 (protein O
fucosyltransferase 1), and PSENEN (presenilin enhancer protein 2
gene).4
Epidermal cysts, multiple keratoacanthomas, squamous cell carcinoma,
abscess, hidradenitis suppurativa, seborrheic keratosis, and pilonidal
cysts are reported to be associated with DDD.2 These
disorders are not present in our case and other family members.
Histopathology of skin biopsy in classical DDD reveals thinning of the
epidermis. Elongated, thinned, and branched (antler like) rete ridges
with increased melanin pigmentation at their tips, but no increase in
the melanocyte number.6 Histopathology of skin biopsy
of our patient also revealed these classical findings. DDD with features
of downs syndrome has not been reported till date in literature.
Karyotyping in daughter would have revealed the association between DDD
and downs syndrome.As the patient denied the intervention, association
could not be established.
It is a rare genetic disorder and only few cases have been reported in
our country. There is no definitive cure for Dowling-Degos disease.
Different treatment options are depigmenting agents such as
hydroquinone, retinoids and laser therapy such as fractional Erbium YAG
laser.7
There is paucity of reported cases of DDD in literature. This condition
should be kept in mind in the differential diagnosis of pigmented
lesions of flexural sites.