Eosinophils in Mycosis Fungoides

Abstract

Early diagnosis of mycosis fungoides (MF) is one of the most challenging problems in dermatopathology, as the histopathologic features of inflammatory dermatoses and MF may show significant overlap. One criterion used to distinguish early MF (patch stage) from dermatitis, which may be currently underutilized, is the presence of eosinophils. A search was performed for cases with a preoperative diagnosis of MF, cutaneous T-cell lymphoma, or dermatitis, which included 29 cases "diagnostic" for MF, 25 cases "suspicious" for MF, and 55 cases of spongiotic dermatitis. We examined tissue sections blinded to diagnosis to obtain an exact eosinophil count. Twenty-nine cases were diagnostic for MF (12 patch, 9 plaque, and 8 tumor stage). The average eosinophil count for cases diagnostic for patch stage MF was 1 eosinophil in 10 (0.11) sections examined. For plaque MF, there was 1 eosinophil in 5 (0.24) sections examined. All tumor stage MF cases showed abundant eosinophils within each section. Twenty-five cases were suspicious for MF (15 patches, 9 plaques, and 1 folliculotropic). The average eosinophil count for the patch lesions was 1 eosinophil in 4 (0.25) sections examined and 2 eosinophils per section for plaque lesions. Forty-five of 55 cases of spongiotic dermatitis had at least scattered eosinophils (>3) in each section. Twenty-three (47%) had eosinophils around most postcapillary venules. Only 3 of 45 patients (6.6%) with biopsies diagnostic or suspicious for patch or plaque stage MF showed >3 eosinophils per tissue section, whereas 45 of 55 (81.8%) biopsies of spongiotic dermatitis had >3. The presence of eosinophils (>3 per tissue section) is statistically significant in differentiating cases diagnostic or suspicious for patch or plaque stage MF from dermatitis (P < 0.0001). Our data indicate that eosinophils are uncommon in cases of patch and plaque MF. When a pathologist is faced with evaluating a biopsy that lacks some of the criteria used to make the diagnosis of patch stage MF, yet demonstrates >3 eosinophils per tissue section, dermatitis is the likely diagnosis. However, in cases where fewer than 3 eosinophils are present in sections, patch stage MF cannot be excluded.

Eosinophils in the skin—a red herring masking lymphoma: a case series

“… 2 As demonstrated by our three cases, the clinical presentation of FMF is extremely variable and includes follicle-based patches, plaques, tumors, keratosis pilaris–like lesions, alopecia and acneiform lesions. Unlike conventional MF, 3 eosinophils are sometimes reported in FMF and tumor stage MF. 4 Our case series highlights the importance of considering FMF in the differential diagnosis of dense lymphoeosinophilic infiltrates, especially if the clinical picture is suggestive as was the case in our patients.…”

Fulminant Mycosis Fungoides with Tissue Eosinophilia: A Unique Presentation of Two Cases with Acro-Periorbital Ulceration and An Aggressive Clinical Course

“…Tissue eosinophils may become numerous with progression of MF to advanced stage tumors and folliculotropic variants [ 1 ], but are uncommon in early stage disease [ 15 – 18 ]. Longstanding MF may progress to a predominantly Th2 immunophenotype, with interleukin (IL) 4 secreting T-cells, eosinophilia, erythroderma, and increased susceptibility to infection [ 16 , 24 – 26 ].…”

“…Tissue eosinophilia can be a useful biomarker in distinguishing MF from inflammatory dermatoses, and among other metrics, the presence of eosinophils has been used as a minor criteria for excluding MF [ 14 , 15 ]. However, studies suggest that as MF progresses from early (patch and plaque) to advanced (tumor, erythroderma, and Sezary syndrome) stage disease, tissue eosinophils become more prominent [ 15 – 18 ].…”

Approach to cutaneous lymphoid infiltrates: When to consider lymphoma?

“…When present, numerous eosinophils and intraepidermal, vase-like shaped, Langerhans cell collections favor the diagnosis of spongiotic dermatitis. [ 33 34 35 36 37 ] Lichenoid dermatoses are distinguished by a dense infiltrate obscuring the dermoepidermal junction coupled with interface changes (vacuolar change, alteration in the shape of the rete ridges, dyskeratotic cells/colloid bodies) dominating the histopathological picture as opposed to appearing only in small foci. [ 38 39 ] PPPD, which typically only affects the skin of lower extremities, is characterized by a perivascular to dense, band-like SDI, which may be accompanied by dermal fibrosis or edema, erythrocyte extravasation, and accumulation of siderophages.…”