Cutaneous pseudo-T-cell lymphomas. A clinicopathologic study of 20 patients

Abstract

The histologic features of 20 patients with cutaneous pseudo‐T‐cell lymphomas other than actinic reticuloid and lymphomatoid papulosis were investigated. Two histologic types of cutaneous pseudo‐T‐cell lymphomas were designated. The band‐like (MF‐like) pattern that simulated mycosis fungoides (MF) and a nodular pattern that mimicked cutaneous T‐cell lymphomas (CTCL) other than MF. Both patterns showed histologic features that generally are not found in CTCL and thus may be helpful in the differential diagnosis from CTCL. However, at present the differential diagnosis between pseudo‐T‐cell lymphomas and CTCL should be based on a combination of clinical and histologic data.

Selected Inflammatory Imitators of Mycosis Fungoides: Histologic Features and Utility of Ancillary Studies

“…41,46,47 Drug-induced pseudolymphoma may be remarkably similar to MF with a dense, bandlike, lymphoid infiltrate in the superficial dermis; mild lymphocyte enlargement and atypia; and intraepidermal lymphocytes (Figure 4, C through H). 40,41,44 Pautrier microabscess-like structures have been reported. 41,46 However, DIP is more commonly found as a single lesion, whereas unilesional MF is uncommon.…”

“…[40][41][42] The clinical presentation ranges from a diffuse, maculopapular eruption to papules, plaques, and/or nodules that may be solitary or multiple. [41][42][43][44][45][46] Rare cases of erythroderma have been reported (Figure 4, A and B). 42,43,47 Medications that may cause drug-induced pseudolymphoma (DIP) are numerous and include antiepileptic drugs (eg, phenytoin, carbamazepine, sodium valproate), as well as other commonly prescribed medications, such as penicillin, b-blockers, angiotensin-converting enzyme inhibitors, and fluoxetine (as reviewed in Ploysangam et al 43 and Albrecht et al 48 ).…”

“…Patients with anticonvulsant-induced pseudolymphoma may develop a characteristic pseudolymphoma syndrome, 40,41,43,44 which many experts include within the spectrum of hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms. 42,45,47,48 Uncommonly, this syndrome may occur with medications other than anticonvulsants.…”

“…41,46 However, DIP is more commonly found as a single lesion, whereas unilesional MF is uncommon. 40,44,[48][49][50] In addition, MF is more likely to involve sun-protected skin and show a variety of clinical morphologies. 4,48 On biopsy, the presence of spongiosis, dyskeratotic keratinocytes, extravasated erythrocytes, pigment incontinence, dermal edema, and/or numerous eosinophils are more supportive of a diagnosis of DIP.…”

“…3,4,15,[52][53][54] Importantly, reactive processes may show loss of T-cell markers, most commonly CD7 and CD5. 19,44,51,53,[55][56][57][58] However, the loss of those markers in inflammatory conditions is often less extensive than it is in MF. 4,59 In addition, many inflammatory dermatoses show a near-equal mixture of CD4 þ and CD8 þ T cells or only a mild predominance, 19,40,44,54,55 although this generalization is far from universal.…”