Differential diagnosis of cutaneous infiltrates of B lymphocytes with follicular growth pattern

CD4-negative variant of CD4+/CD56+ hematodermic neoplasm: description of three cases

BACKGROUND

CD4+/CD56+ hematodermic neoplasm (HN) (blastic natural killer (NK)-cell lymphoma) is a rare entity characterized by dense, monomorphous infiltrates of medium-sized cells with blastic appearance and a characteristic immunophenotype (positivity for CD4, CD56 and CD123). The combination of CD4 and CD56 positivity is thought to be so striking that it has been used to name this entity.

METHODS

Three cases of HN with ambiguous phenotypic profile were included in this study. In all cases, phenotypic, molecular and in situ hybridization studies were carried out.

RESULTS

All three cases showed an aberrant phenotype with negativity for CD4.

CONCLUSIONS

CD4-negative or CD56-negative cases of HN have been rarely reported in the literature and represent a diagnostic problem. Our three cases confirm that CD4 is not always expressed in these neoplasms. The term 'CD4+/CD56+ hematodermic neoplasm' adopted in the World Health Organization-European Organization for Research and Treatment of Cancer classification of cutaneous lymphomas may be misleading and should probably be revised in the light of all data published in the literature.

Clinicopathological features of primary cutaneous B-cell lymphomas from an academic regional hospital in central Italy: no evidence of Borrelia burgdorferi association

We reviewed the clinico-pathological features of 73 primary cutaneous B-cell lymphomas (PCBCLs), diagnosed in 10 years in Marche region in central Italy, which included 16 marginal zone lymphomas (MZL), 33 follicle centre lymphomas (FCL) and 24 diffuse large B cell lymphomas (DLBCL). We also investigated the presence of Borrelia burgdorferi in tissues by polymerase chain reaction. Differences in age, sex, location site, response to therapy, disease recurrence and 5-year disease-specific survival were observed among the 3 histological groups. Specific DNA sequences of Borrelia burgdorferi were not detected in any of the 73 cases of PCBCL. We conclude that PCBCLs in Marche region behave according to the literature data and do not seem to be associated with Borrelia burgdorferi. Additional investigations should be performed on other possible etiologies, at least in our geographical area.

The morphologic spectrum of primary cutaneous anaplastic large T-cell lymphoma: a histopathologic study on 66 biopsy specimens from 47 patients with report of rare variants

BACKGROUND

Primary cutaneous anaplastic large T-cell lymphoma (PCALCL) is a well-defined entity with prognostic differences from the nodal counterpart [nodal anaplastic large cell lymphoma (NALCL)]. Several histological variants of NALCL have been characterized (common, lymphohistiocytic and small cell). However, studies on morphological variants of PCALCLs are lacking.

METHODS

We analyzed retrospectively the clinicopathologic features of 66 biopsies from 47 patients (M : F = 27 : 20; median age: 53 years; mean age: 51.8 years; range: 14-82) with PCALCL, in order to better characterize the spectrum of this unusual neoplasm.

RESULTS

The 'common variant' was the most frequent (40.4%). In contrast to NALCL, in PCALCL, marked reactive infiltrates are more commonly present. In fact, 26 cases were classified as 'inflammatory type' (15 cases) and 'lymphohistiocytic' (11 cases). Concerning the predominant cell morphology, large anaplastic cells (33%) were almost as frequent as large pleomorphic (36%) and small to medium-sized cells (26%). We reported for the first time in the skin 2 rare cases with the predominance of large cells with a 'signet-ring'-like appearance. Epidermotropism and presence of eosinophils were found in a proportion of cases in all PCALCL variants.

CONCLUSIONS

PCALCL is characterized by variable histopathological presentations and a broad cytomorphologic spectrum.

Ectopic lymphoid tissues and local immunity

Ectopic or tertiary lymphoid tissues develop at sites of inflammation or infection in peripheral, non-lymphoid organs. These tissues are architecturally similar to conventional secondary lymphoid organs, with separated B and T cell areas, specialized populations of dendritic cells, well-differentiated stromal cells and high endothelial venules. Ectopic lymphoid tissues are often associated with the local pathology that results from chronic infection or chronic inflammation. However, there are also examples in which ectopic lymphoid tissues appear to contribute to local protective immune responses. Here we review how ectopic lymphoid structures develop and function in the context of local immunity and pathology.

Cutaneous B-cell pseudolymphoma at the site of vaccination

Pseudolymphomas are a rare complication of vaccination, presenting with dense lymphoid infiltrates and prominent follicular pattern. We report our observations on 4 patients with vaccination-induced B-cell pseudolymphoma (all females; age range 19 to 60 years; median: 34.5 years). Clinically 3 patients presented with subcutaneous nodules and 1 presented with a large, indurated, erythematous plaque. Histology revealed in all cases dense lymphoid infiltrates in the subcutaneous fat with prominent follicular pattern. The follicles displayed features of reactive germinal centers (normal mantle zone, presence of tingible body macrophages, normal proliferation). Necrotic areas surrounded by palisaded histiocytes were seen in 3 biopsies from 2 patients. A mixed-cell infiltrate with eosinophils and plasma cells was present in all cases. In addition, histiocytes with granular basophilic cytoplasm could be observed around the focal area of necrosis or within the inflammatory infiltrate. Follow-up was available for 3 patients. One patient was alive with persistent disease 6 months after the first observation. Two patients were treated with local radiotherapy and are alive and free of disease after 12 and 72 months, respectively. One of these two patients had a second pseudolymphoma on the contralateral arm after a new injection of vaccine. Cutaneous pseudolymphoma after vaccination should be distinguished histopathologically from low-grade cutaneous B-cell lymphomas (follicle center cell lymphoma, marginal zone lymphoma) and from other B-cell pseudolymphomas with prominent follicular pattern requiring different treatment (eg, Borrelia burgdorferi-induced lymphocytoma cutis).

Primary cutaneous follicle center lymphoma -'crosti lymphoma': what can we learn?

In 1951, Crosti reported on seven patients with 'reticulo-histiocytoma of the back' who presented with figurate erythematous plaques and nodules on the back or lateral trunk. Reticulo-histiocytoma of the back was later classified as a primary cutaneous follicle center lymphoma (PCFCL). A definitive diagnosis of the condition is frequently delayed because of a relative lack of clinical symptoms and difficulties in interpretation of the histologic findings. Indeed, a number of primary cutaneous B-cell lymphomas have been mislabeled as pseudolymphomas in the past. We present a case of PCFCL that initially demonstrated predominantly small T lymphocytes on histology. These findings were interpreted as an inflammatory pseudolymphomatous reaction. However, small lymphocytes, whether B or T cells, in early lesions of cutaneous B-cell lymphomas should not automatically be considered 'reactive.' Persistent antigenic stimulation of lymphocytes in a neoplastic process or by an antigen, for example, Borrelia burgdorferi, can lead to transformation and cell division with development of large blast cells. In our patient, the initial scarcity of B lymphocytes also led to further diagnostic difficulties. Although the association of primary cutaneous B-cell lymphoma with Borrelia infection is known, there are still difficulties in differentiating the condition from pseudolymphoma. Such difficulties can in part be ascribed to the morphologic changes such lymphomas can undergo over time. The initially small number of B cells that may be seen at first in PCFCL infiltrates may increase in number in longer-standing lesions. It is also important to recognize that inability to verify monoclonality should not exclude the diagnosis of lymphoma.

Lymphoproliferative lesions of the skin

Diagnosis and differential diagnosis of cutaneous lymphoproliferative disorders is one of the most difficult areas in dermatopathology, and biopsies are often taken to rule out a cutaneous lymphoma in patients with "unclear" or "therapy-resistant" skin lesions. Histopathological features alone often enable a given case to be classified to a diagnostic group (eg, epidermotropic lymphomas), but seldom allow a definitive diagnosis to be made. Performing several biopsies from morphologically different lesions is suggested, especially in patients with suspicion of mycosis fungoides. Immunohistochemistry is often crucial for proper classification of the cases, but in some instances is not helpful (eg, early lesions of mycosis fungoides). Although molecular techniques provide new, powerful tools for diagnosing cutaneous lymphoproliferative disorders, results of molecular methods should always be interpreted with the clinicopathological features, keeping in mind the possibility of false positivity and false negativity. In many cases, a definitive diagnosis can be made only on careful correlation of the clinical with the histopathological, immunophenotypical and molecular features.

Cutaneous B-cell Pseudolymphoma due to Paraphenylenediamine

Lymphomatoid contact dermatitis is a form of pseudolymphoma that was first described in 1976 by Orbaneja et al. Since that initial report, a number of allergens have been reported to cause this type of pseudolymphoma. Most cases involve hyperplasia of T cells. We describe a case of cutaneous B-cell pseudolymphoma due to paraphenylenediamine. This report underscores the importance of thorough history and observation when assessing patients with suspected lymphoproliferative processes.

The protean spectrum of non-Hodgkin lymphomas with prominent involvement of subcutaneous fat

BACKGROUND

Subcutaneous T-cell lymphoma (STCL) represents a controversial entity and a confused concept in the field of cutaneous T-cell lymphomas (CTCLs). Recently, alpha/beta+/CD8+ STCL has been recognized by the new World Health Organization (WHO)-European Organization for Research and Treatment of Cancer (EORTC) classification of primary cutaneous lymphomas as a distinct entity in the group of CTCLs.

OBSERVATIONS

We reviewed a series of 53 biopsies from 26 patients (F : M = 19:7; median age: 48; range 18-87) of cutaneous B- and T-cell lymphomas characterized by prominent involvement of the subcutaneous tissue. We could classify our cases according to the following seven categories--(i) STCL: n = 16; (ii) extranodal NK/T-cell lymphoma, nasal type: n = 2; (iii) cutaneous gamma/delta T-cell lymphoma: n = 2; (iv) anaplastic CD30+ large T-cell lymphoma: n = 1; (v) diffuse large B-cell lymphoma, secondary cutaneous: n = 3; (vi) lymphoplasmacytic lymphoma, secondary cutaneous: n = 1; (vii) specific cutaneous manifestations of myelogenous leukemia: n = 1.

CONCLUSIONS

We demonstrated the protean nature of lymphomas with prominent involvement of the subcutaneous fat tissues. The term STCL should be restricted to a homogeneous group of cases characterized morphologically by an exclusive involvement of subcutaneous tissues, immunohistochemically by a T-cytotoxic alpha/beta phenotype, and biologically by a relatively good prognosis.

Molecular cytogenetic evidence of t(14;18)(IGH;BCL2) in a substantial proportion of primary cutaneous follicle center lymphomas

In contrast to nodal follicular lymphoma, limited data exist on genetic changes in primary cutaneous follicular lymphoma (primary cutaneous follicle center lymphoma according to WHO-EORTC). The detection rate of the BCL2 rearrangement, representing the characteristic t(14;18)(q32;q21) underlying follicular lymphoma, by polymerase chain reaction (PCR) has been reported to vary over a wide range (0%-41%), and only a few cases have been studied by molecular cytogenetic techniques such as fluorescence in situ hybridization (FISH). In this study, 27 primary cutaneous follicle center lymphomas were analyzed by FISH and the results compared with those obtained by PCR. FISH demonstrated translocations affecting the immunoglobulin heavy chain locus (IGH) in 14 of 27 cases (52%): a t(14;18)(q32;q21) involving BCL2 was found in 11 cases (41%), a t(3;14)(q27;q32) affecting BCL6 in 2 cases (7%), and in 1 case the partner gene of IGH could not be identified. Interestingly, PCR did not detect BCL2 rearrangement in any case. These data suggest that the t(14;18)(q32;q21) frequently occurs in primary cutaneous follicular lymphoma. The reason(s) why BCL2 rearrangements escape the detection by PCR is (are) not clear but could be due to BCL2 mutations, breakpoints outside the amplified DNA, or a high load of somatic mutations.

The New World Health Organization–European Organization for Research and Treatment of Cancer Classification of Cutaneous Lymphomas

The WHO-EORTC classification of cutaneous lymphomas is a good start to unifying nomenclature, a necessity before coherent consensus diagnoses can be made. There are three provisional diagnoses in this new classification that are not covered in detail in this review because they are rare diseases that still require further study for definitive classification. Much remains to be elucidated about cutaneous lymphomas, but understanding of the major entities within the new classification is an important first step in understanding these diverse diseases.

Cutaneous lymphoid hyperplasia and other lymphoid infiltrates of the breast nipple: a retrospective clinicopathologic study of fifty-six patients

This study characterizes the clinicopathological spectrum of lymphoproliferations involving the breast nipple and/or areola. Morphologic, immunohistochemical, molecular-genetic, and clinical features of 58 specimens from 56 patients were analyzed. They were re-diagnosed as cutaneous lymphoid hyperplasia (CLH, n = 44); other benign lymphoid infiltrates (OBLI, n = 8); peripheral T-cell lymphoma, not otherwise specified (n = 1); cases with overlapping features of CLH and B-cell lymphoma (n = 3), one of them composed of spindle cells. Cutaneous lymphoid hyperplasia infiltrates were dense, composed mainly of B cells forming follicles with germinal centers (GC). Cutaneous lymphoid hyperplasia frequently showed features suggesting a malignancy as coalescing follicles with non-polarized germinal centers lacking mantle zones, and smudged infiltrates of lymphoid cells spreading into collagen (often as "Indian files"), smooth muscle, vessel walls, and nerve sheaths. Only two cutaneous lymphoid hyperplasias recurred; otherwise all patients are without disease (mean follow-up 62 months). Monoclonal rearrangement of immunoglobulin heavy chain gene was detected in five, and of T-cell receptor gamma gene in two cutaneous lymphoid hyperplasias using polymerase chain reaction (PCR), but the patients fared well too. In 47% of cases Borrelia burgdorferi was detected by polymerase chain reaction and/or serology, of which one was monoclonal. We conclude that cutaneous lymphoid hyperplasia is the most common lymphoproliferation of the breast nipple, rarely recognized clinically, and often overdiagnosed histologically as lymphoma.

Clinicopathologic, Immunophenotypic, and Molecular Cytogenetic Fluorescence In Situ Hybridization Analysis of Primary and Secondary Cutaneous Follicular Lymphomas

Although primary cutaneous follicular lymphoma (FL) is considered a distinct variant of FL in the World Health Organization classification ("cutaneous follicle center lymphoma"), its biologic relationship to nodal FL remains controversial. The clinical, morphologic, immunophenotypic, and molecular cytogenetic features of 17 patients with primary cutaneous FL were studied and compared with 16 patients with secondary cutaneous FL. The head and neck region was the most frequent site at initial skin presentation in both the primary and secondary cases. Among the primary cases, 29% of the 31 biopsies were grade 1, 48% grade 2, 13% grade 3, and 10% grade 3 with diffuse large B-cell (DLBCL) areas. Among the secondary cases, 38% of the 29 skin biopsies were grade 1, 45% grade 2, 3% grade 3, and 7% grade 3 with DLBCL areas with two not evaluable. A floral-like pattern was observed in 32% of primary FL but only 5% of secondary cases. Histologic progression was found in 21% of patients. CD10 expression was demonstrated in 90% (27 of 30) of primary cases and 96% (22 of 23) of secondary cases. Bcl-6 was expressed in all cases tested. Bcl-2 expression was detected in 57% (17 of 30) of the primary cases (100% of grade 1, 43% of grade 2, 40% of grade 3), whereas all secondary cases were bcl-2 positive (P=0.0002). The t(14;18) translocation was identified by interphase fluorescence in situ hybridization (FISH) in biopsies from 31% (4 of 13) of the patients with primary FL compared with 77% (10 of 13) of those with secondary lymphoma (P <0.05). Seven of the 17 (41%) patients with primary disease had cutaneous relapse, including 1 who also developed nodal disease. Bcl-2 positivity was seen in 4 of these 7 patients. Eight of the 16 (50%) patients with secondary FL had cutaneous relapse. Primary and secondary cutaneous FL share many clinical and phenotypic features, but primary cases may have some distinctive morphologic features, more frequently lack bcl-2 protein, and often lack the t(14;18) translocation. These findings suggest that primary cutaneous FL are distinctive and often but not always have a pathogenesis different from most of nodal and secondary cutaneous FL.