Disscusion
EN is fundamentally a hamartoma of keratinocytes and occasionally
adnexal structures. It mostly develops in the first years of life,
although late-onset presentation has also been reported ¹´⁴. Martinez et
al report a 27 years old woman who developed EN during pregnancy. They
proposed hormonal and immunological alternations during pregnancy as a
possible explanation ⁵.
More than 10 histopathological variants of EN have been described so far
and papillomatosis, hyperkeratosis, and acanthosis are the most common
findings. Epidermolytic hyperkeratosis is an uncommon variant ⁶.
Epidermolytic hyperkeratosis is characterized by granular and vacuolar
degeneration of keratinocytes in the spinous and granular layer of
epidermis along with hyperkeratosis. In addition to EN, this
histological pattern can be seen in epidermolytic ichthyosis, specific
kinds of palmoplantar keratodermas and epidermolytic acanthoma ⁷.
The dermoscopy view of the epidermolytic hyperkeratosis EN is mostly
similar to other kinds of EN containing: large brown circles and the
absence of the pigment network ²´⁸. Carbotti et al first described large
brown circles in EN and correlated it histologically to the way
pigmented keratinocytes lie down around dermal papillae ². Demographics
and dermoscopic features of epidermolytic hyperkeratosis EN being
reported in the literature are summarized in Table 1.
The clinical differential diagnosis of this lesion includes wart and
seborrheic keratosis which can be excluded by considering the unique
clinical pattern of EN (blaschkoid distribution) and lack of cytopathic
viral effects, which are seen in the wart.
Full-thickness surgical excision is the treatment, but in large lesions
hypertrophic scar and keloid formation is the side effect. Other
treatment modalities include electrofulguration, cryosurgery, and
dermabrasion, but they make scarring. Topical agents (calcipotriol,
steroids, retinoic acid) were not effective. Soft and flat nevi were
responsive to ablative lasers, but the lesions may recur after
non-surgical procedures. So because of the side effects of extensive
surgery a conservative approach is logic in the case of extensive
lesions9.
In conclusion epidermolytic hyperkeratotic EN is a rare variant of EN,
which can be congenital or developed later in adulthood. Although the
histopathological finding of this variant is unique and is different
from other variants of EN, the dermoscopic feature is the same and can
be considered an important clue in the diagnosis of different variants
of EN.