SMALL AND LARGE PLAQUE PARAPSORIASIS

Introduction:

Chronic idiopathic dermatosis.

Epidemiology:

Common in middle age and elderly.
Peak during fifth decade of life.
Male predominance

Pathogenesis:

Unknown.
Both disorders characterized by superficial cutaneous lymphoid infiltrates of CD4 T cells.
Some cases of large plaque are manifestation of patch stage of MF, there is 10 to 35 % progression of large plague to more overt forms of lymphoma.

Clinical Features:

Symptoms:

Generally asymptomatic or mildly pruritic.

Location:

Trunk, extremities.(favor sun protected sites)

Signs:

Despite word plaque lesions consist of patches.
They may wax and wane early in the disease but typically become persistent and slowly progress over years.

Small Plaque Para-psoriasis:

Round Oval patches less than 5 cm in diameter.
Variably erythematous but less intense than psoriasis.
Covered with a fine scale.
Those with a yellow stain have been termed Xantho-Erythrodermia perstans.

Variant: Digitate dermatosis
Presents as elongated finger like patches symmetrically distributed on flanks.
Are exception to 5 cm rule as may be as long as 10 cm or more along their long axis.
Very low risk of progression to MF.

Large Plaque Para-psoriasis.

Presents as variable erythematous round and irregular shaped scaly patches that are larger that 5 cm.
May or may not exhibit clinical triad of atrophy, telangiectasia and hyper/hypopigmentation.(Piokiloderma vasculare atrophicans)

Variants: Retiform para-psoriasis AKA para psoriasis variegata or para-psoriasis lichenoides.

There are widespread ill-defined patches in a net like or zebra-stripe pattern.
Virtually all of these Retiform pattern progress to overt MF.

Pathology:

Small  Plaque Para-psoriasis

Mild non specific spongiotic dermatitis and parakeratosis.

Large Plaque Para-psoriasis

Interface lymphocytic infiltrate with a variable degree of lichenoid features
Some case contain atypical lymphoid cells and are indistinguishable from patch stage of MF.

Treatment:

Small Plaque Para-psoriasis:

Reassure patients that risk of development of MF is none.
May be followed with out treatment.
Treatment options include

First Line

Topical Steroids
Topical Coal Tar
Bexarotene
Protopic
Imiquimod.

2nd line:

Photo-therapy

Large Plaque Para Psoriasis

All patients should be treated.
First and second line treatment same as above.
Patients who meet the histopathological criteria of MF should be treated as such.