Introduction:
Mycosis fungoides (MF) is the most common variant of primary skin T-cell
lymphoma, affecting nearly half of the cases of skin T-cell lymphoma. It
is most prevalent among the middle aged and elderly adults of all
races1. MF typically manifests as an indolent
cutaneous eruption with erythematous scaly patches or plaques and may
progress to a generalized erythroderma and/or cutaneous tumors or invade
the extra-cutaneous tissues, and in the early stages it usually mimics
other common skin disorders including psoriasis and
eczema2. Diagnosis of MF is challenging due to the
nonspecific clinical and pathological findings especially at the early
stages, making it highly possible to get misdiagnosed for
years3. Final diagnosis is confirmed through
pathological findings of skin biopsy, and treatment is available with
desirable therapeutic outcome in many cases3. Several
treatment options are available for the treatment of MF including
skin-directed therapy consisting of topical corticosteroids,
phototherapy, topical chemotherapy, topical retinoids and radiotherapy
for the early stages and systemic therapy including interferone-alpha,
oral retinoids including bexarotine, acitretin, histone deacetylase
inhibitors, fusion toxin denileukin diftitox, and chemotherapy drugs for
more advanced stages. The prognosis is highly depended on the type and
extent of skin involvement the presence of extracutaneous involvement,
while most patients have an indolent and incurable
course4,5. Psoriasis is one of the most prevalent
chronic inflammatory disorders of the skin with an auto-immune origin.
Manifestations include erythematous scaly plaques that are clinically
similar to psoriasiform MF. Psoriatic patients are at increased risk of
skin malignancies. A diagnosis of psoriasis is usually made clinically
and treatment options mainly include immunosuppressants and biologic
agents6,7.
In this article we report an uncommon presentation of psoriasiform MF in
a patient who was diagnosed with psoriasis and managed accordingly for a
long time as well as the diagnostic and therapeutic challenges
encountered with a review of the literature on similar cases and their
clinic-pathological findings.