The clinical features and histopathologic patterns of folliculotropic mycosis fungoides in a series of 38 cases

When mycosis fungoides seems not to be within the spectrum of clinical and histopathological differential diagnoses

The most prevalent primary cutaneous T-cell lymphoma, mycosis fungoides (MF), is characterized by the development of plaques and nodules after an erythematous patchy phase that is non-specific. An infiltrate of atypical small- to medium-sized cerebriform lymphocytes in the superficial dermis, with variable epidermotropism, is the histopathological hallmark of the disease. In more advanced stages of the illness, large-cell transformation may be seen. Early diagnosis of MF can be very challenging based only on histopathologic or clinical findings, so it is critical to have a clinical-pathological correlation. Many atypical variants of MF that deviate from the classic Alibert-Bazin presentation of the disease have been described over the past 30 years, sometimes with different prognostic and therapeutic implications. Clinically or histopathologically, they can mimic a wide range of benign inflammatory skin disorders. To make a conclusive diagnosis in these cases, it is recommended to take multiple biopsies from various lesions and to carefully correlate the clinical and pathological findings. We have outlined the various facets of the illness in this review, positioning MF as a "great imitator", with an emphasis on the more recently identified variations, differential diagnosis, and its benign mimics.

Mycosis fungoides and Sézary syndrome: clinical presentation, diagnosis, staging, and therapeutic management

Mycosis fungoides (MF) and Sézary syndrome (SS) are cutaneous T-cell lymphomas. MF is the most common cutaneous lymphoma, and it is classified into classic Alibert-Bazin MF, folliculotropic MF, pagetoid reticulosis, and granulomatous slack skin, each with characteristic clinical presentation, histopathological findings, and distinct clinical behaviors. SS is an aggressive leukemic variant of cutaneous lymphoma, and it is characterized by erythroderma, lymphadenopathy, and peripheral blood involvement by malignant cells. There is a wide range of dermatological manifestations of MF/SS, and prompt recognition is essential for early diagnosis. Skin biopsy for histopathology and immunohistochemical analysis is imperative to confirm the diagnosis of MF/SS. Histopathology may also provide information that may influence prognosis and treatment. Staging follows the TNMB system. Besides advanced stage, other factors associated with poorer prognosis are advanced age, male gender, folliculotropism in histopathology of patients with infiltrated plaques and tumors in the head and neck region, large cell transformation, and elevated lactate dehydrogenase. Treatment is divided into skin-directed therapies (topical treatments, phototherapy, radiotherapy), and systemic therapies (biological response modifiers, targeted therapies, chemotherapy). Allogeneic bone marrow transplantation and extracorporeal photopheresis are other treatment modalities used in selected cases. This review discusses the main clinical characteristics, the histopathological/immunohistochemical findings, the staging system, and the therapeutic management of MF/SS.

Spiky/keratosis-pilaris-like early follicular mycosis fungoides: A clinicopathologic study of 20 cases with extended follow-up

BACKGROUNDS

Follicular mycosis fungoides (FMFs) is a distinct form of T-cell lymphoma whose course is considered aggressive.

METHODS

A retrospective study with long-term follow-up of 20 patients diagnosed with spiky/keratosis-pilaris-like FMF between 2008 and 2017 was conducted.

RESULTS

Twelve males and eight females were identified, with a mean age at first diagnosis of 59 years (range 42-86). Hyperkeratotic follicular papules were the sole clinical finding in 16 of 20 patients. A diagnostic delay between first symptom development and initial diagnosis was frequent (mean 42 months). The head/neck region was concurrently affected only in two patients. Disease stage at diagnosis was IA in two patients (10%) and IB in 18 (90%). Five patients had almost complete lesion regression, whilst there was only a slight improvement, without regression in 14. Two patients developed infiltrated papules, comedones, and small cysts during follow-up. Only one patient progressed to tumor stage (IIB) five years after the first diagnosis. The mean follow-up was seven years (range: 12-180 months). None of them died of cutaneous lymphoma.

CONCLUSIONS

FMF presenting with only spiky/keratosis-pilaris-like lesions have an excellent prognosis at medium-term follow-up. Early recognition of patients with this peculiar FMF presentation might lead to identifying prognostic factors.

High incidence of adnexotropism in cytotoxic cutaneous lymphomas

BACKGROUND

Primary cutaneous gamma-delta T-cell lymphoma (PCγδTCL) and primary cutaneous aggressive epidermotropic T-cell lymphomas (PCAETCL) are rare aggressive cytotoxic cutaneous lymphomas (CyCL) often difficult to diagnose. Histopathologically, PCAETCL and PCγδTCL may resemble mycosis fungoides (MF) and the presence of adnexotropism in CyCL (CyCL) contributes to this diagnostic challenge, especially in the setting of atypical and double-negative phenotypes.

METHODS

In this retrospective study clinical data and histopathological section of 91 patients were analyzed for signs of clinical and histopathological signs adnexotropism.

RESULTS

Adnexotropism was identified in 48.4% (44/91) of cases, including PCAETCL (40.9%, 18/44), PCγδTCL and cytotoxic cutaneous lymphomas, not otherwise specified (CyCTCL, NOS) (43.2%, 19/44 and 15.9%, 7/44). Comparison between disease-related mortality with Kaplan-Meier survival analysis of non-adnexotropic vs adnexotropic CyCL did not show any significant difference between the two groups (P = 0.8). Clinically they present with patches, plaques, and tumors and commonly with ulceration, but follicular prominence or alopecia are rare. Clinical signs of adnexotropism such as alopecia and hypo- or anhidrosis were rarely seen.

CONCLUSION

Adnexotropism is a common finding in CyCL, especially in PCAETCL. Adnexotropic CyCL may be histopathologically difficult to distinguish from folliculotropic mycosis fungoides. A comprehensive IHC panel should be routinely performed in such cases.

Eosinophilic folliculitis, eosinophilic dermatosis of hematologic malignancy and acneiform follicular mucinosis: Two case reports and a review of the literature highlighting the spectrum of histopathology

Within the literature, there is overlap in the histopathological features described in eosinophilic folliculitis associated with chronic lymphocytic leukemia (CLL), eosinophilic dermatosis of hematologic malignancy, and acneiform follicular mucinosis. These disorders are described with varying degrees of superficial and deep lymphocytic and eosinophilic inflammation demonstrating perivascular, perifollicular, and folliculocentric involvement with or without follicular mucin deposition. Given significant histopathological overlap, these diagnoses may represent a continuum on a spectrum of dermatoses. Here, we present two cases with histopathological elements that reflect components of this clinicopathological spectrum and compare our findings with previously reported cases to compare and contrast reported features. Our first case is a 71-year-old African American man with long-standing CLL who developed a pruritic erythematous papular eruption on the face and chest with biopsy revealing a dense folliculotropic lymphocytic infiltrate with conspicuous eosinophils and follicular mucinosis. Our second case is a 70-year-old Caucasian man recently diagnosed with CLL/small lymphocytic lymphoma who developed an erythematous papular rash on the neck and face with biopsy revealing superficial and deep perivascular and periadnexal lymphocytic inflammation with scattered eosinophils. Characterization of our two cases and comparison with available literature suggest that these disorders may represent a continuum of dermatoses.

Lichen planus follicularis tumidus: Immunotyping of the inflammatory infiltrate with focus on plasmacytoid dendritic cells

Lichen planus follicularis tumidus (LPFT) is a rare clinicopathological variant of lichen planus (LP), clinically presenting with red-to-violaceous plaques studded with comedo-like lesions and keratin-filled milia-like cysts. Histopathologically, LPFT is characterized by cystically dilated follicular infundibula in the dermis, surrounded by a dense lichenoid lymphoid infiltrate with an associated interface reaction. We describe the clinicopathological features of an additional case of LPFT, focusing on the number and distribution of CD123(+) TCF4(+) plasmacytoid dendritic cells (pDCs). In our case, pDCs represented approximately 5% of the total inflammatory infiltrate, predominantly exhibiting a lichenoid distribution around the infundibula with no evidence of cluster formation, thus ruling out cutaneous lupus erythematosus. Our report is the first to describe the number and distribution of pDCs in LPFT. The results of our immunohistochemical analysis corroborate the notion that LPFT should be regarded as a rare variant of LP.

Acneiform Presentations of Folliculotropic Mycosis Fungoides

BACKGROUND

Folliculotropic mycosis fungoides (FMF) is a variant of cutaneous T-cell lymphoma that has clinical overlap with a variety of inflammatory follicular unit disorders. However, we describe distinctive presentations of FMF with acneiform features that can be diagnostically challenging, leading to diagnostic delay.

OBJECTIVE

To highlight the importance of histopathologic and immunohistochemical evaluation for diagnostic confirmation of presumed inflammatory follicular unit-based disorders that are unusual in presentation or unresponsive to standard therapies.

METHODS

A cross-sectional retrospective study of 5 consecutive patients with a histopathologic diagnosis of FMF was conducted. The clinical, histopathologic, immunophenotypic, and molecular genetic features of cases are presented.

RESULTS

We describe 5 patients with clinical and histopathologic presentations of FMF masquerading as hidradenitis suppurativa, furunculosis, or acne vulgaris (age range 34-66 years, 4:1 female to male). Clinical morphologies included open and closed comedones, inflammatory pustules, papules and nodules, follicular papules with keratotic plugging, cysts, and scarring involving the face, trunk, and intertriginous areas. All patients failed to respond to standard therapies, including topical and oral antibiotics, topical and oral retinoids, or topical corticosteroids, before receiving the diagnosis of FMF. Lesional skin biopsies showed a perifollicular CD4-positive T-lymphocytic infiltrate with pilotropism, intrafollicular mucin deposition, foreign-body granulomatous inflammation, acute inflammation, and follicular epithelial necrosis. None had concurrent systemic mycosis fungoides.

LIMITATIONS

Small retrospective cohort study.

CONCLUSION

We present these cases to expand the clinical and histopathologic spectrum of FMF that may strikingly resemble acneiform disorders and to highlight the importance of diagnostic reconsideration with histopathologic evaluation.

Folliculotropic mycosis fungoides: Clinical characteristics, treatments, and long-term outcomes of 53 patients in a tertiary hospital

Folliculotropic mycosis fungoides (FMF) is characterized by a broad clinical spectrum and worse prognosis compared to classical MF. This study aimed to evaluate the clinical characteristics, treatment modalities and long-term outcome and risk factors for progression and survival of FMF patients. We conducted a single-center retrospective study and reviewed 53 patients diagnosed with FMF between 1990 to 2019 in a referral center at Ankara University, Turkey. Regarding to stage at diagnosis, 24 patients (45.3%) had advanced-stage disease (≥IIB). Follicular papules was observed in 66% and alopecia in 49.1% of the cases. Forty-three patients (81.1%) suffered from pruritus. The majority of the patients (92.4%) had at least one systemic therapy. Complete remission was achieved in 24.5% of the patients. The median time of overall survival (OS) was 50 months (range 9-324 months) and 5-year and 10-year OS was 83% and 69%, respectively. Twenty-eight (52.3%) patients progressed to more advanced stages and seven (13.2%) patients died due to MF during the follow-up period. FMF is associated with a progressive course and in most patients, skin-directed therapies were found to be inefficient to control the disease and multiple systemic therapeutic agents were required to control the disease.

Plaque stage folliculotropic mycosis fungoides: histopathologic features and prognostic factors in a series of 40 patients

BACKGROUND

Folliculotropic mycosis fungoides (FMF) is a distinct variant of mycosis fungoides. Recent studies recognized indolent and aggressive subgroups of FMF, but there is controversy how patients presenting with plaques should be classified. The present study describes the histopathologic features of 40 FMF plaques. The aim of the study was to identify risk factors for disease progression and poor outcome in this group.

METHODS

Clinical, histopathological, and immunophenotypical data from 40 patients with plaque stage FMF were reviewed and analysed for risk factors for disease progression and survival.

RESULTS

After a median follow-up of 80 months, disease progression occurred in 20 of 40 patients. Percentage of atypical cells, cell size, percentage of Ki-67+ cells, and co-existent interfollicular epidermotropism, but not the extent of perifollicular infiltrates, were associated with disease progression and reduced survival, while extensive follicular mucinosis was associated with increased survival.

CONCLUSIONS

This study underlines that FMF patients presenting with plaques represent a heterogeneous group and that a subgroup of these patients may have an indolent clinical course. It further shows that histological examination is a valuable tool to differentiate between indolent and aggressive disease.

CD8+ cytotoxic mycosis fungoides: a retrospective analysis of clinical features and follow-up results of 29 patients

BACKGROUND AND OBJECTIVE

Less than 5% of cases of mycosis fungoides (MF) present with a cytotoxic/suppressor CD8⁺ phenotype. This study aimed to evaluate the clinical characteristics, treatment modalities, and clinical course in CD8⁺ MF patients.

METHODS

In a retrospective analysis of 353 MF patients in a referral center at Ankara University, Turkey, 29 patients that were diagnosed with CD8⁺ MF were included in the study.

RESULTS

CD8⁺ MF cases constituted 8.2% of all MF patients. The age at the time of diagnosis ranged between 6 and 81 years with a median value of 46 years. The female-to-male ratio was 1.41. Patients presented with erythematous scaly (69%), hyperpigmented (58.6%), poikilodermic (17.2%), and hypopigmented (17.2 %) patches/plaques. The most common sites of involvement were the trunk and lower extremities. The most common comorbidity was hypertension (24.1%, n: 7) with 13 patients (44.8%) having a history of at least one autoimmune disease. At the time of diagnosis, 93.2% of the patients had early-stage disease, and 6.8% of the patients had advanced stage. The mean follow-up period was 6.68 ± 6.04 years (range 1-28 years). Most of the patients were treated with skin-directed therapies. Complete remission was achieved in 17 (58.6%) patients, eight (27.6%) patients had partial remission, and four (13.8%) patients had stable disease.

CONCLUSIONS

We concluded that CD8⁺ MF is associated with an indolent course and in most patients, skin-directed therapies were found to be efficient to control the disease.

Scleromyxedematous Changes in a Patient With Long-Standing Mycosis Fungoides Who Progressed to Sézary Syndrome

Mycosis fungoides (MF) variants with different clinicopathologic and immunohistochemical features have been well-delineated. We report a case of scleromyxedematous changes arising in a patient with long-standing MF who progressed to Sézary syndrome (SS) shortly afterward. Total-skin electron-beam radiation therapy resulted in an excellent response, controlling both the MF/SS and the scleromyxedematous lesions; however, the patient died few months later. Although mucin deposition has been described in association with MF/SS (mainly follicular mucinosis in folliculotropic MF), there are limited reports in the literature on dermal mucinosis and scleromyxedematous changes in MF/SS. The mechanism of this association and its prognostic implications requires further investigation.

Immune privilege disruption in folliculotropic mycosis fungoides: investigation of major histocompatibility complex antigen expression

BACKGROUND

Folliculotropic mycosis fungoides (FMF) is a cutaneous T-cell lymphoma mainly affecting the hair follicle, which seems to represent a place of immune privilege phenomenon.

OBJECTIVES

To explore a possible role of immune privilege (IP) in FMF analyzing the major histocompatibility complex (MHC) expression.

METHODS

Immunohistochemistry for HLA-G and MHC-II was performed to formalin-fixed paraffin-embedded cutaneous skin biopsies of FMF patients (n = 43), conventional mycosis fungoides (CMF; n = 13), alopecia areata (AA; n = 13), and normal scalp skin (NS; n = 12).

RESULTS

HLA-G expression was lower in FMF (34%: 14/41) and CMF (18%: 2/11) groups compared to alopecia areata (92%:11/12) and normal scalp skin group (100%: 12/12). MHC-II expression in hair follicle was greater in the FMF group (18/42: 43%) compared to AA (0%) and NS (0%). HLA-G and MHC-II expression in cellular infiltrate had no difference among FMF and CMF groups and was different compared to the AA group.

CONCLUSIONS

Our data support the hypothesis of disruption of immune privilege based on the lower expression of HLA-G and higher expression of MHC-II in the follicular epithelium in mycosis fungoides compared to alopecia areata and normal scalp skin. The lack of difference between FMF and CMF groups did not support the role of these molecules as a driver of folliculotropism. The expression of MHC molecules seems to be different between neoplastic and inflammatory infiltrates. The definitive significance of expression of the MHC molecules remains unclear, and more studies are necessary to fully understand the role of these molecules in cutaneous lymphomas.

Cutaneous T-cell Lymphoma

Cutaneous T-cell lymphomas comprise a heterogeneous group of diseases characterized by monoclonal proliferations of T lymphocytes primarily involving skin, modified skin appendages, and some mucosal sites. This article addresses the basic clinical, histologic, and immunohistochemical characteristics of this group of diseases, with additional attention to evolving literature on dermoscopy, reflectance confocal microscopy, flow cytometry, and molecular data that may increasingly be applied to diagnostic and therapeutic algorithms in these diseases. Select unusual phenotypes or diagnostic examples of classic phenotypes are demonstrated, and flags for consideration while making a pathologic diagnosis of cutaneous T-cell lymphoma are suggested.

Multidisciplinary Management of Mycosis Fungoides/Sézary Syndrome

PURPOSE OF REVIEW

Diagnosis and management of mycosis fungoides and Sézary syndrome (MF/SS) require accurate clinicopathological correlation and a multidisciplinary approach. We reviewed major advances in the field regarding diagnostic and prognostic tools as well as skin-directed therapies (SDTs) and systemic agents for MF/SS published in the past 2 years.

RECENT FINDINGS

Improved technology (T-cell receptor high-throughput sequencing) and increased multicenter collaboration (Cutaneous Lymphoma International Consortium) have led to diagnostic/prognostic advances. Concurrently, numerous genomic studies have enhanced understanding of disease pathogenesis. Advances in SDTs include topical resiquimod, a novel potent Toll-like receptor (TLR) agonist; consensus CTCL phototherapy guidelines; and use of low-dose radiation therapy. Novel systemic therapies for advanced disease of note include targeted antibody drug conjugates (brentuximab vedotin), immune checkpoint inhibitors, and allogeneic hematopoietic stem cell transplantation (HSCT). Our "toolbox" to diagnose and treat the spectrum of MF/SS continues to expand. Further characterization of genomic data going forward will enable a rational approach to selecting and combining therapies to improve patient care.

Clinical characteristics, risk factors and long-term outcome of 114 patients with folliculotropic mycosis fungoides

Folliculotropic mycosis fungoides (FMF) is a distinct variant of mycosis fungoides (MF) where atypical T-cells invade the hair follicles. The objective was to assess the clinical features, risk factors for progression, long-term outcome and response to treatment modalities in a large cohort of FMF patients. We, therefore, conducted a single-center retrospective study, reviewing 114 patients with FMF seen from 1987 to 2015 at the cutaneous T-cell lymphoma clinic of the MD Anderson Cancer Center. The mean age at diagnosis of FMF was 57.1 ± 13.5 years. The male to female ratio was 1.2:1. MF stage IA (n = 50, 43.9%) was the most common diagnosed stage, followed equally by stages IB and IIB (n = 23, 20.2%, respectively). Eighty-six patients (75.4%) suffered from pruritus. Concomitant hair loss was observed in 37 (32.5%) subjects. The median number of different treatment modalities used per patient was 4 (range 1-12). Low-dose radiation was beneficial in clearing therapy refractory lesions. The overall survival was influenced by several factors, including advanced age (>65), late stages and the presence of large cell transformation (LCT). Thirty-three of 113 patients (29.2%) progressed to more advanced stages and 26 (23.0%) died, with the cause of death being MF in 11 (9.7%) subjects. In conclusion, patients with FMF have a worse overall 10-year survival rate compared with other MF variants. Several factors, including stage, advanced age and the presence of LCT impact survival. Multiple different treatment approaches may be needed to achieve a good clinical response and to prevent disease progression.

Recommendations for treatment in folliculotropic mycosis fungoides: report of the Dutch Cutaneous Lymphoma Group

BACKGROUND

Folliculotropic mycosis fungoides (FMF) is an aggressive variant of mycosis fungoides (MF) and generally less responsive to standard skin-directed therapies (SDTs). Recent studies distinguished indolent (early-stage FMF) and more aggressive (advanced-stage FMF) subgroups. The optimal treatment for both subgroups remains to be defined.

OBJECTIVES

To evaluate initial treatment results in patients with early- and advanced-stage FMF.

METHODS

A study was undertaken of 203 patients (84 early-stage, 102 advanced-stage, 17 extracutaneous FMF) included in the Dutch Cutaneous Lymphoma Registry between 1985 and 2014. Type and results of initial treatment were retrieved from the Dutch Registry. Main outcomes were complete remission (CR); sustained complete remission; partial remission (PR), > 50% improvement; and overall response (OR; CR + PR).

RESULTS

Patients with early-stage FMF were treated with nonaggressive SDTs in 67 of 84 cases resulting, respectively, in CR and OR of 28% and 83% for monotherapy topical steroids, 0% and 83% for ultraviolet B (UVB), and 30% and 88% for psoralen plus ultraviolet A (PUVA). In patients with advanced-stage FMF these SDTs were less effective (combined CR and OR 10% and 52%, respectively). In patients with advanced-stage FMF local radiotherapy (CR 63%; OR 100%), total skin electron beam irradiation (CR 59%; OR 100%) and PUVA combined with local radiotherapy (CR 5%, OR 75%) were most effective.

CONCLUSIONS

The results of the present study demonstrate that not all patients with FMF should be treated aggressively. Patients with early-stage FMF may benefit very well from standard SDTs also used in early-stage classic MF and have an excellent prognosis.

Vernachlässigte klinische Merkmale der follikulotropen Mycosis fungoides: eine große klinische Fallserie

HINTERGRUND UND ZIEL

Als seltene Form der Mycosis fungoides (MF), ist die follikulotrope MF (FMF) durch ein breites Spektrum klinischer Symptome gekennzeichnet. Dazu gehören, neben den vorherrschenden follikulären Läsionen, auch viele atypische Manifestationen. Das Ziel der vorliegenden Studie war eine klinische Bewertung von FMF-Patienten, unter besonderer Berücksichtigung von vernachlässigten dermatologischen Merkmalen.

PATIENTEN UND METHODIK

Insgesamt wurden 27 FMF-Patienten aus dem 572 Patienten umfassenden MF-Register unserer Abteilung retrospektiv bezüglich ihrer Demographie sowie der klinischen Merkmale, Behandlungsformen, Nachsorge und Therapieergebnisse bewertet.

ERGEBNISSE

Neben den bekannten klinischen Symptomen der FMF fanden wir Lichen-spinulosus-artige Läsionen mit begleitender Hypopigmentierung (n = 3) und Alopezie (n = 2), infiltrierte/erhabene, erythematöse Plaques im Gesicht, die zunächst als Lupus tumidus angesehen wurden (n = 2), pseudotumorale Läsionen, die klinisch eine MF im Tumorstadium vortäuschten (n = 1), dauerhafte Exkoriationen (n = 1), erythematöse, Rosazea-artige Papeln im Gesicht (n = 1) sowie kuppelförmige, asymptomatische, mit Muzin gefüllte (in der Histologie) Papeln/Knoten (n = 2), die andere krankheitsbedingte Läsionen überlagerten. Es kamen mehrere Therapieansätze mit unterschiedlichem Ergebnis zur Anwendung. Acht (29,6 %) Patienten hatten FMF im Spätstadium.

SCHLUSSFOLGERUNGEN

Das Bewusstsein für vernachlässigte klinische Symptome kann wesentlich dazu beitragen, verspätete Diagnosen dieser aggressiven MF-Variante zu verringern.

Folliculotropic Mycosis Fungoides: Clinical and Histologic Features in Five Patients

BACKGROUND

Alopecia can be a manifestation of mycosis fungoides (MF); however, the prevalence is unknown.

AIMS

We sought to describe the clinicopathologic presentation of alopecia in patients with diagnosis of MF.

METHODS

A retrospective analysis of patients with biopsy-proven MF, who were evaluated at our cancer center from 2002 to 2012, was performed to identify patients with alopecia.

RESULTS

Five patients with alopecia were identified from reviewing of 157 patients with MF. The male:female ratio was 3:2, and the mean age of patients was 42.8 years. Two of these patients showed patchy hair loss on scalp which was clinically identical to alopecia areata. In remaining three patients, hair loss was seen in areas of MF lesions, and epidermal changes consisted of patch- and plaque-type lesions of MF, tumors, and follicular lesions (follicular MF) were also present. In two of these patients, lymphadenopathy without any visceral involvement was detected.

CONCLUSIONS

Alopecia was observed in 5 (3.18%) patients with MF, which makes it a rare finding, which included alopecia areata-like patchy loss in 2 and alopecia within MF lesions in 3.

Unusual variants of mycosis fungoides

Conventional presentations of mycosis fungoides may be diagnostically challenging, particularly in light of the controversial boundaries defining the disease. Variant presentations of this cutaneous T-cell lymphoma add a further layer of complexity, requiring a sophisticated and informed perspective when evaluating lymphoid infiltrates in the skin. Herein we discuss well-defined (WHO-EORTC) variants pagetoid reticulosis, granulomatous slack skin and folliculotropic mycosis fungoides as well as less well-defined morphologic/architectural variants, and divergent immunohistochemical presentations of this typically indolent T-cell lymphoproliferative disease.