Lichen Sclerosus with Histopathologic Features Simulating Early Mycosis Fungoides

Abstract

Mycosis fungoides (MF) is a cutaneous T-cell lymphoma characterized in its early stages by a superficial band-like infiltrate with epidermotropism of lymphocytes without particularly atypical cytologic features. Even though clinicopathologic presentation is diagnostic in typical cases, some inflammatory skin disorders can simulate the histopathologic features of early MF. In this study we present data on 9 patients affected by lichen sclerosus (LS) (M:F ratio 8:1; age range 7-75 years; mean age 31.3 years; median age 13 years), who presented with histopathologic features simulating early lesions of MF. The histopathologic picture was characterized in all cases by a dense, band-like infiltrate of lymphocytes within the superficial dermis, with exocytosis of lymphocytes within the lower part of the epidermis. The papillary dermis was expanded and showed focally coarse bundles of collagen simulating MF. The typical signs of LS were either absent or present only focally. Molecular analyses of the TCRgamma gene rearrangement performed with the polymerase chain reaction (PCR) technique revealed a polyclonal smear in eight cases, and a monoclonal band in one. Our study shows that LS can present with histopathologic features simulating early MF. Especially in cases revealing a monoclonal population of T lymphocytes by PCR, the correct diagnosis may be overlooked without proper clinical information and clinicopathologic correlation. Lichen sclerosus should be added to the list of cutaneous T-cell pseudolymphomas.

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

“…19,[25][26][27][28] In addition, the papillary dermis may display coarse or wiry collagen bundles. 26 Developed lesions of LSA show hyperkeratosis, follicular plugging, and epidermal atrophy. Basement membrane thickening, papillary dermal edema, and broad, dermal collagen hyalinization are characteristic.…”

“…Haloed lymphocytes are less common in LSA but may occur. 26 In addition, the intraepidermal lymphocytes of LSA tend to be confined to the lower epidermis, whereas those in MF are more likely to show pagetoid spread.…”

“…11, 16,17,26 In addition, LSA tends to show a zonal pattern of subepidermal fibrosis, with focal areas of the dermis replaced by dense collagen. 26 Interface changes, such as vacuolar alteration of basal keratinocytes, dyskeratotic keratinocytes, and blurring of the dermal-epidermal junction by lymphoid cells, also favor LSA, 26 although they have also been reported in MF.…”

“…26 Interface changes, such as vacuolar alteration of basal keratinocytes, dyskeratotic keratinocytes, and blurring of the dermal-epidermal junction by lymphoid cells, also favor LSA, 26 although they have also been reported in MF. 5,11,12,14,16 At least focal, vacuolar alteration of basal keratinocytes has been reported in 21% to 70% of MF cases, 5,11-14 whereas associated dyskeratotic keratinocytes are less common, 11,13,16 and a lymphocytic infiltrate that obscures the dermal-epidermal junction is not usually seen.…”

“…5 Conversely, significant lymphocyte atypia and Pautrier microabscesses support a diagnosis of MF. 4,7,11,16,17,26,28 Finally, the clinical setting is a critical distinguishing feature. A background of patches, plaques, or tumors characteristic of MF, argues in favor of MF.…”