Primary cutaneous pleomorphic small T-cell lymphoma. A review of 11 cases. The French Study Group on Cutaneous Lymphomas

Cutaneous lymphoproliferative disorders: Back to the future

In the 1980s, immunohistochemistry and clonality analyses became instrumental in the recognition and definition of new types of cutaneous T-cell lymphoma (CTCL) and cutaneous B-cell lymphoma (CBCL) and the development of new classifications. By accepting loss of pan-T-cell antigens and clonal T-cell receptor gene rearrangements as important criteria to differentiate between benign and malignant T-cell proliferations, and monotypic immunoglobulin light-chain expression and clonal immunoglobulin gene rearrangements as crucial criteria to distinguish between benign and malignant B-cell proliferations, many cases, until then diagnosed as cutaneous lymphoid hyperplasia or pseudolymphoma, were reclassified as primary cutaneous CD4+ small/medium T-cell lymphoma (PCSM-TCL) or primary cutaneous marginal zone lymphoma (PCMZL), respectively. However, in recent years there is growing awareness that neither these immunohistochemical criteria nor demonstration of T-cell or B-cell clonality is specific for malignant lymphomas. In addition, many studies have reported that these low-grade malignant CTCL and CBCL have an indolent clinical behavior and an excellent prognosis with disease-specific survival rates of or close to 100%. As a result, recent classifications have downgraded several low-grade malignant cutaneous lymphomas to lymphoproliferative disorder (LPD). Both the 5th edition of the WHO classification (2022) and the 2022 International Consensus Classification (ICC) of mature lymphoid neoplasms reclassified PCSM-TCL as primary cutaneous CD4+ small/medium T-cell LPD and primary cutaneous acral CD8+ T-cell lymphoma as primary cutaneous acral CD8+ T cell LPD. While the 2022 ICC introduced the term "primary cutaneous marginal zone LPD," in the 5th edition of the WHO classification PCMZL is maintained. In this review we describe the background and rationale of the continually changing terminology of these conditions and discuss the clinical consequences of downgrading malignant lymphomas to LPDs.

[Granulomatous reaction pattern of the skin : Interstitial granulomatous dermatitis - lymphoma - vasculitis]

A particular diagnostic situation in the classification of a granulomatous dermatitis results when no circumscribed granulomas but instead a diffuse interstitial histiocytic inflammatory infiltrate, a granulomatous vasculitis or a neoplastic lymphocytic infiltrate is found. Interstitial granulomatous dermatitis was originally described in patients with arthritis. Later, it was recognized that there are also associations with other usually immunological diseases. Differentiating between interstitial granulomatous dermatitis and the interstitial form of granuloma annulare, early morphea and variants of borreliosis or scleromyxedema as well as interstitial granulomatous drug reaction can be very difficult. In long-standing cutaneous granulomatous infiltrates, T‑cell lymphoma should be excluded. Occasionally only a small number of atypical lymphocytes can be found. The detection of a monoclonal T‑cell expansion is then particularly helpful. Only recently, a CD8-positive granulomatous cutaneous T‑cell lymphoma was described which occurred in patients with immunodeficiencies. A granulomatous vasculitis in the skin is extremely rare. According to the Chapel Hill classification from 2012, systemic granulomatous vasculitis is equated with giant cell arteritis. Extracutaneous large arteries are involved. On rare occasions, involvement of the temporal artery can result in skin necrosis. More commonly granulomatous infiltrates in combination with vasculitis can be observed, whereby various infectious diseases, sarcoidosis and nodular vasculitis should be considered. Granulomatosis with polyangiitis (formerly Wegener's granulomatosis), presents in the skin as leukocytoclastic vasculitis. Here granulomas are extremely rare.

Cutaneous T-cell lymphoma: 2011 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis fungoides (MF) or Sézary syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

Tumor, node, metastasis, and blood (TNMB) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral, or blood involvement are generally approached with biologic-response modifiers, denileukin diftitox, and histone deacetylase inhibitors before escalating therapy to include systemic, single-agent chemotherapy. Multiagent chemotherapy may be used for those patients with extensive visceral involvement requiring rapid disease control. In highly-selected patients with disease refractory to standard treatments, allogeneic stem-cell transplantation may be considered.

Classification of cutaneous T-cell lymphoma: from Alibert to WHO-EORTC

Cutaneous T-cell lymphomas (CTCLs) represent a heterogeneous group of neoplasms originating from skin-homing T cells that show considerable variation in clinical presentation, histological appearance, immuno- phenotype, and prognosis. This review provides a historic overview of the classification of CTCLs from the first description of a patient with mycosis fungoides in 1806 to the recently published WHO-EORTC classification. Practical guidelines for the usage of the WHO-EORTC classification and relevant features of new or newly defined entities such as subcutaneous panniculitis-like T-cell lymphoma, extranodal NK/T-cell lymphoma, nasal type, primary cutaneous aggressive CD8-positive cytotoxic T-cell lymphoma, and cutaneous gamma/delta T-cell lymphoma are presented. The aim of this review is to contribute to a better communication between dermatologist and pathologist and in this way to a better diagnosis and classification of CTCLs.

WHO/EORTC classification of cutaneous lymphomas 2005: histological and molecular aspects

The new WHO/EORTC classification for cutaneous lymphomas comprises mature T-cell and natural killer (NK)-cell neoplasms, mature B-cell neoplasms, and immature hematopoietic malignancies. It reflects the unique features of lymphoproliferative diseases of the skin, and at the same time it is as compatible as possible with the concepts underlying the WHO classification for nodal lymphomas and the EORTC classification of cutaneous lymphomas. This article reviews the histological, phenotypical, and molecular genetic features of the various nosological entities included in this new classification. These findings always have to be interpreted in the context of the clinical features and biologic behavior.

AIM

To review the histological, phenotypical and molecular genetic features of the various nosological entities of the new WHO/EORTC classification for cutaneous lymphomas.

METHODS

Extensive review of the literature cited in Medline and own data of the authors.

RESULTS

The WHO/EORTC classification of cutaneous lymphomas comprises mature T-cell and NK-cell neoplasms, mature B-cell neoplasms and immature hematopoietic malignancies. It reflects the unique features of primary cutaneous lymphoproliferative diseases.

CONCLUSION

This classification is as much as possible compatible with the concept of the WHO classification for nodal lymphomas and the EORTC classification of cutaneous lymphomas. The histological, phenotypical and molecular genetic features always have to be interpreted in the context of the clinical features and biologic behavior.

Primary cutaneous lymphomas: a review with current treatment options

Primary cutaneous T- and B-cell lymphomas are a heterogenous group of diseases with varied clinical presentations and prognosis. The use of new molecular, histological, and clinical criteria have enhanced the recognition of primary cutaneous T- and B-cell lymphomas. Compared to their nodal counterpart they have a different clinical behavior and therefore require a different treatment approach. Independent predictive factors identified clinically, histologically, and by immunopheno- and immunogenotyping are essential to assess the appropriate treatment for each subtype. The European Organization for Research and Treatment of Cancer (EORTC) Cutaneous Lymphoma Study Group provide a classification of cutaneous lymphomas taking into account of the histological and molecular features. Based on this classification we will provide a summary of the current medical literature in diagnosis, treatment, and prognosis for primary cutaneous lymphomas with emphasis on new treatment strategies.

Cutaneous lymphomas with prominent granulomatous reaction: a potential pitfall in the histopathologic diagnosis of cutaneous T- and B-cell lymphomas

The presence of a granulomatous reaction in lesions of cutaneous lymphomas has been described in the past in several cases. Especially in mycosis fungoides, a "granulomatous" variant of the disease has been well characterized. We studied the clinicopathologic features of cutaneous lymphomas with prominent granulomatous reaction, including both cutaneous T-cell lymphomas and B-cell lymphomas (primary cutaneous lymphoma 22, secondary cutaneous lymphoma one). Biopsies of 23 patients with histopathologic features of cutaneous T-cell lymphoma or cutaneous B-cell lymphoma with prominent granulomatous reaction were included in this study. A prominent granulomatous reaction was defined as the presence of a granulomatous component exceeding 25% of the dermal infiltrate. There were 14 cases of mycosis fungoides, two of subcutaneous panniculitis-like T-cell lymphoma, four of small/medium pleomorphic T-cell lymphoma, one of follicle center cell lymphoma, one of large B-cell lymphoma, and one of secondary cutaneous peripheral T-cell lymphoma. Altogether, a prominent granulomatous reaction could be observed in 1.8% of all patients with cutaneous lymphoma (primary or secondary) registered in the files of the Department of Dermatology of the University of Graz (Graz, Austria), demonstrating that there is a distinct, albeit small, proportion of cases revealing this peculiar reaction pattern. In seven cases a misdiagnosis of granulomatous dermatitis preceded the correct diagnosis for a period of 1-216 months, suggesting that sequential biopsies and complete phenotypic and molecular genetic analyses should be carried out in cases of "unusual" granulomatous dermatitis.

Pseudolymphomatous folliculitis: a clinicopathologic study of 15 cases of cutaneous pseudolymphoma with follicular invasion

We report the clinical, histopathologic, and immunohistologic features of 15 cases of pseudolymphomatous folliculitis (PLF). The patients comprised seven males and eight females (mean age, 38.6 years; age range, 2-67 years). All patients had dome-shaped or flat-elevated nodules suggestive of cutaneous lymphoid hyperplasias (CLHs). The lesions were solitary in all 15 cases, except in one case with duplex lesions. All lesions were located on the face and measured less than 1.5 cm. In 14 cases with one lesion each, five lesions showed rapid regression after incisional biopsy, whereas the remaining nine underwent excisional biopsy. In the case with duplex lesions, one regressed spontaneously after excisional biopsy of the other. Histopathologically, all PLFs showed dense lymphocytic infiltrates from the dermis to the subcutis simulating cutaneous lymphomas. The walls of hair follicles in all cases were enlarged and irregularly deformed with their epithelium blurred by lymphocytic infiltrates; we called this change "activation" of hair follicles. In nine cases, many atypical lymphocytes were intermingled; three of these cases had been misdiagnosed as cutaneous T-cell lymphoma at other institutions. Immunohistologically, 10 and 5 cases showed predominantly B cells and predominantly T cells, respectively. Remarkably, all lesions showed increased numbers of perifollicular histiocytes expressing anti-S-100 protein and CD1a, and seven lesions showed histiocytes in aggregates. We conclude that PLF is a subset of CLH with characteristic clinical and pathologic features showing perifollicular clustering of T-cell-associated dendritic cells with activation of pilosebaceous units. PLF is an entity to be differentiated from malignant lymphomas and other cutaneous pseudolymphomas.

Involvement of the tongue by lymphomatoid papulosis

We report on a case of lymphomatoid papulosis (LyP) with involvement of the tongue. The patient was a 34-year-old Japanese man. Three reddish, centrally depressed, slightly elevated nodules were evident on the dorsal tongue, along with lesions elsewhere on the skin. One of them was biopsied and exhibited a superficial and deep, perivascular and interstitial mixed cellular infiltrate including atypical lymphoid cells, lymphocytes, neutrophils, and histiocytes. The patient also showed rhythmical recurrence of reddish papules and ulcerated nodules on the trunk, extremities, and anogenital area. Histologically, these papules showed a dense, wedge-shaped mixed cellular infiltrate in the dermis, which included medium and large atypical lymphoid cells, lymphocytes, neutrophils, and histiocytes. Immunoperoxidase staining for CD30 was positive in the cell membrane and cytoplasm of the atypical cells. We could not find other reports of LyP involving the tongue. Systemic treatment with interferon (INF)-alpha2a was dramatically effective in inhibiting recurrence of the eruption.

Interleukin-7 receptor expression in cutaneous T-cell lymphomas

Keratinocyte-derived interleukin-7 (IL-) is a potent growth factor for some cutaneous T-cell lymphomas (CTCL). We investigated the expression of IL-7 receptor (IL-7R) in several types of cutaneous and nodal lymphomas. We studied 44 CTCL (13 mycosis fungoides, six Sézary syndromes, eight pleomorphic small cell, and 17 pleomorphic medium and large cell), 10 lymphomatoid papulosis (LP), five cutaneous B-cell lymphomas, and five reactive lymphocytic infiltrates. Twenty nodal T-cell lymphomas, and three reactive lymph nodes were also analysed. Frozen sections were stained with monoclonal antibodies directed against IL-7R, CD25, CD30 and T antigens (CD3, CD2, CD5, CD7, CD4, CD8), using the alkaline phosphatase-antialkaline phosphatase technique. No expression of IL-7R was observed in cutaneous B-cell lymphomas, benign cutaneous lymphoid infiltrates, and reactive lymph nodes. IL-7R was expressed by more than 20% of lymphoid cells in 50-75% of all histological subtypes of CTCL, and by more than 50% of cells in 15-50%. IL-7R was expressed by more than 20% and 50% of cells in 40% and 10% of nodal large T-cell lymphomas, respectively. Eighty-nine per cent of CTCL and LP expressing IL7-R also expressed CD25+, compared with 58% of IL-7R--CTCL and LP (P < 0.05). No association of IL7-R and CD30 expression was found. In conclusion, CTCL frequently express IL-7R. This expression is not related to the epidermotropic characteristic of the infiltrate. In CTCL and LP, IL-7R expression is associated to CD25 expression, but not to CD30 expression.