Answer: Pityriasis rosea
Criteria for diagnosis
histopathologically: The findings of
a hyperplastic epidermis with mounds of parakeratosis and with foci
of spongiosis in the spinous zone, in combination with a
perivascular infiltrate of lymphocytes around dilated venules of
the superficial plexus and extravasated erythrocytes there, are
those of pityriasis rosea.
histopathologically: Histopathologic changes present
in erythema annulare centrifugum cannot be distinguished from those
of pityriasis rosea. In allergic contact dermatitis or nummular
dermatitis, spongiosis is usually more prominent and epidermal
hyperplasia is more pronounced. In pityriasis rosea, spongiosis
occurs typically in foci, sometimes even spongiotic vesiculation is
seen, while in other parts of the epidermis spongiosis is
Criteria for diagnosis
clinically: Oval, orange-to red-papules and plaques
covered by a collarette of fine scales located on the trunk are
characteristic of pityriasis rosea.
clinically: There is none.
correlation: The lesion is papular
because of the hyperplastic epidermis and the inflammatory cell
infiltrate in the papillary dermis. The scale is a consequence of
parakeratosis. The typical orange-to-light red color is a result of
dilated, erythrocyte-filled venules and of extravasated
erythrocytes in the papillary dermis.
Options for therapy predicated on knowledge of
histopathologic findings: Pityriasis rosea is a
transient disease that is usually asymptomatic, therefore, no
therapy is necessary.
1) In the
majority of cases, pityriasis rosea can be diagnosed clinically,
while the histopathologic findings are undistinguishable from those
of erythema annulare centrifugum. In this patient, however, neither
the clinical findings nor the histological findings are diagnostic
by themselves and clinico-pathological correlation enables accurate
diagnosis to be rendered.
Collarettes of scale represent the clinical correlate of residual
mounds of parakeratosis that have been shed in the center.
Spongiotic dermatitides with an accelerated turnover of
keratinocytes manifest themselves histologically with spongiosis
and later with mounds of parakeratosis that house globules of
lesions in this patient are early in the course of the disease
because clinically the scale hardly is discernible, and
histopathologically spongiosis dominates over the changes of
epidermal hyperplasia and parakeratosis.