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Which general statement regarding T-cell pseudolymphoma is INCORRECT?

A) These lesions both clinically and histopathologically may resemble mycosis fungoides and may occasionally exhibit clonality via T-cell-receptor rearrangement analysis.

B) The natural history of T-cell pseudolymphoma is that of a chronic dermatosis that either transforms into lymphoma or eventually resolves spontaneously.

C) These lesions may be histopathologically characterized by nodular dermal infiltrates with scattered large CD30+ T cells.

D) T-cell pseudolymphoma is immunohistochemically defined by lost expression of pan-T-cell markers CD2, CD5, or CD7.

E) Reported associations include HIV disease, UV-light exposure, and various medications.

The correct answer is D.

T-cell pseudolymphoma (aka T-cell dyscrasia) is a controversial diagnostic category of T-cell infiltrates that are characterized by chronic dermatoses of unknown significance (Table 12-1A). These infiltrates may be band like (resembling mycosis fungoides) or diffuse/nodular with scattered large CD30+ T cells (resembling anaplastic large cell lymphoma). In general, these eruptions share histopathologic features with both reactive inflammatory conditions and lymphoma; therefore, oftentimes represent an equivocal diagnosis of lymphoma (cannot be ruled out). There is a vast number of conditions that some have argued should be included in the band-like category (ie, large plaque parapsoriasis, pityriasis lichenoides chronica, alopecia mucinosa, pigmented purpuric dermatosis, actinic reticuloid, and chronic dermatitis of HIV disease). The incidence of transformation into mycosis fungoides is extremely variable among these conditions. In general, there is extremely low risk for pityriasis lichenoides chronica and pigmented purpuric dermatosis; however, there is a significant risk for large plaque parapsoriasis and alopecia mucinosa. There is currently much debate as to whether these high-risk conditions actually represent a form of indolent mycosis fungoides. A few authors have proposed the designation “endogenous T-cell dyscrasia” for these conditions, especially the high-risk entities. When these infiltrates are associated with medications, they are referred to as lymphomatoid drug eruptions or drug-associated reversible T-cell dyscrasias (Table 12-1B). Withdrawal of the offending medication leads to resolution of the eruption; however, the time course to resolution may be prolonged. Microscopically, where mycosis fungoides is associated with lymphocyte epidermotropism and minimal to no spongiosis and keratinocyte dyskeratosis, the band-like T-cell pseudolymphomas exhibit significant spongiosis with Langerhans cell–rich vesicles and/or true interface activity with variable keratinocyte dyskeratosis. Both conditions may contain atypical small lymphocytes with cerebriform nuclear contour irregularity (Sézary cells); however, these cells are found in much smaller numbers in pseudolymphoma (Table 12-1C).

Lymphomatoid hypersensitivity reaction (mycosis fungoides–like drug eruption) in a patient on amitriptyline. A band-like dermal lymphocytic infiltrate is present and shows haphazard epidermotropism with minimal spongiosis; in other areas not shown, the epidermis was spared, unlike ...

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