Lymphomas of the Vulva: A Review of the MITO Rare Cancer Group

Simple Summary Vulvar lymphomas are uncommon diseases and account for less than 0.5% of gynecological cancers and 1.5% of all NHLs. The various types of lymphomas have recently been identified as separate diseases and not as morphological variations of the same disease, according to the World Health Organization classification. They often represent the secondary localization of systemic disease, and diffuse large B-cell lymphoma is the most common type. We also considered cases of vulvar T-cell lymphomas. The data analysis highlighted the difficulty of diagnosis and the need to resort to biopsy–histological examination, as well as molecular methods. The correctness of the diagnosis directly affects appropriate therapeutic management, which requires an adequate surgical approach that can be integrated with chemotherapy and radiotherapy. Abstract Since they are very rare tumors, lymphomas of the vulva are often not properly recognized. Patients with vulvar lymphoma are generally elderly and the classical manifestation of the disease is a vulvar mass. No significant age differences have been found between primary and secondary lymphoma. To make a correct diagnosis, it is therefore necessary to use not only histological examination but also the genetic and molecular profile in order to establish optimal therapeutic management. Literature analysis confirm the good prognosis of this disease.


Introduction
After having achieved an international consensus among pathologists, hematologists, radiologists, and clinical oncologists, the 2008 and 2017 editions of the "World Health Organization (WHO) Classification of Tumours of the Hematopoietic and Lymphoid Tissues Cancers 2024, 16, 2102 2 of 15 guidelines for malignant lymphoma diagnosis" [1,2] defined multiple entities, according to the REAL classification [3], which incorporated morphology, immunophenotyping, genomics and clinical features.In 2022, the fifth edition of the World Health Organization Classification of Haematolymphoid Tumours defined a systemic evolution of the prior classifications [1,4].
Since they account for 5% of all malignancies, malignant lymphomas constitute a heterogeneous group of diseases arising from clonal lymphocyte proliferation.A total of 10% are Hodgkin lymphomas (HLs) of classical and non-classical sub-types, while the majority (90%) are identified as non-Hodgkin lymphomas (NHLs), which include B-cell, T-cell, and natural killer (NK) cell types [5].
Immunohistochemistry is the only analysis that distinguishes between B-and T-cell lineages.
Non-Hodgkin lymphomas (NHLs) account for 70-80% of all lymphomas, and their classic clinical characteristic manifestation is typically in lymph node stations or in other lymphoid tissues, like bone marrow and spleen.In 20-24% of cases, the localization of lymphoma disease may also involve extranodal sites, such as the nervous central system, gastrointestinal tract, salivary glands, lung, thyroid, and skin [6].
Lymphomas are defined as "primary cutaneous" if the primary diagnosis is in the skin, in the absence of evidence of extra-cutaneous disease.
Primary cutaneous lymphomas represent a heterogeneous group of T-cell and Bcell (CTCLs and CBCLs) that exhibit different clinical behaviors and prognoses from histologically similar systemic lymphomas that can affect the skin secondarily.For this reason, they need different types of treatment.
Classification systems for non-Hodgkin lymphomas, such as the European Organization for Research and Treatment of Cancer (EORTC) classification for primary cutaneous lymphomas and the World Health Organization (WHO) classification for tumors of hematopoietic and lymphoid tissues, include primary cutaneous lymphomas as separate entities [7,8].
In developed countries, CTCLs constitute approximately 75%-80% of all primary cutaneous lymphomas, and CBCLs 20%-25% [7].Despite their peculiar clinical and histological features, cutaneous CTCLs and CBCLs are somewhat difficult to study due to their rarity.Having a completely different clinical behavior and prognosis than morphologically similar nodal lymphomas that may have secondary localization in the skin, they need a different type of treatment [9].
The objective of this review is to provide gynecological oncologists and hematologists with a detailed and precise update based on the latest WHO classification and on the most recent clinical, pathological, and biological characteristics of lymphoma of the vulva, a rare and poorly known tumor.

Materials and Methods
A systematic search of the literature until March 2024 was performed in the following electronic databases: PubMed, the Cochrane Library, Embase, Web of Science, and Medline databases.The article research was carried out according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework [10], as presented in Figure 1.The protocol was not registered.In the article, it is possible to find the following search keywords, which were used alone or in combination: "Lymphomas", "Vulvar lymphoma", and "Cutaneous B-cell/T-cell Lymphomas".
independently evaluated for eligibility by the two authors.Any discordance between the two authors was solved by discussion among the two senior reviewers (G.C. and G.M.).Data were collected from the most relevant scientific articles published from 1937 to May 2021.Reviews or articles including lymphomas in the outside of the vulva and vulvar lymphomas in pregnant women were excluded.In total, 39 articles, for 54 cases, were selected to be included in this review and are reported in Table 1.Information was derived from relatively large single-institution studies, multi-center consortium projects, and population-based registry analyses [11].In particular, we considered case series and case reports published in English.For what concerns the publication period, no limitations were imposed.Two authors (F.M. and C.A.) independently reviewed the titles and abstracts of all of the eligible articles.Every possible duplicate was removed.The full texts of potentially suitable studies were then independently evaluated for eligibility by the two authors.Any discordance between the two authors was solved by discussion among the two senior reviewers (G.C. and G.M.).
Data were collected from the most relevant scientific articles published from 1937 to May 2021.Reviews or articles including lymphomas in the outside of the vulva and vulvar lymphomas in pregnant women were excluded.In total, 39 articles, for 54 cases, were selected to be included in this review and are reported in Table 1.CR/ NED at 6months Table legend: NA, not available; RT, radiotherapy; DLCL, diffuse large cell lymphoma; HL, Hodgkin lymphoma; NHL, Non-Hodgkin lymphoma; LPL, lymphoplasmacytic lymphoma; DLBCL, diffuse large B-cell lymphoma; CLL, chronic lymphocytic leukemia; FL, follicular lymphoma; FLCL, follicular large cell lymphoma; MF, mycosis fungoides; PTCL, peripheral T-cell lymphoma.MZL, marginal zone lymphoma; PLBCL, primary cutaneous large B-cell lymphomas; PCDLBCL-LT, primary cutaneous diffuse large B-cell lymphomas-leg type; AECTCL, aggressive epidermotropic cytotoxic T-cell lymphoma; PD, progression disease; RD, relapsed disease; PR, partial response; SD, stable disease; CR, complete response; DOD, died of disease; NED, no evidence of disease.

Incidence of Lymphomas of Female Genital Tract
Like all primary cutaneous lymphomas, the rare primary genital lymphoma may not be correctly diagnosed.
In women, genital lymphomas occur in different areas, such as the vulva, ovary, and uterine corpus.They are defined as primary if, at diagnosis, the following criteria are met: (1) the disease is confined to the female genital tract, irrespective of the involvement of one or more sites (e.g., ovary and uterine corpus), with no evidence of disease elsewhere (full investigation failed to reveal any evidence of disease elsewhere); (2) peripheral blood and bone marrow do not contain any abnormal cells indicating lymphoma; (3) no remote organs are involved within 6 months of diagnosis.
Genital lymphomas are defined as secondary if they are diagnosed after or concurrent with lymph node detection [36].
When there is a lack of evidence of extra-cutaneous disease, vulvar lymphomas are grouped as primary cutaneous lymphomas, which embrace distinct lymphoma entities [36].They often display a completely different clinical profile and prognosis to histologically similar nodal lymphomas, which may involve the skin secondarily and require different treatment [4].

Clinical and Pathological Features of Vulvar Lymphoma
In spite of the common symptoms, lymphomas are different diseases in that they show clinical-pathological features and prognoses [53], as reported in the literature and described in Table 1.
Patients affected by vulvar lymphoma are older than patients with lymphomas that affect any other gynecological site.No significant age differences have been found between primary and secondary lymphoma.
On a clinical level, vulvar lymphomas occur with swelling, itching, burning, discomfort, or pain, usually associated with fast-growing, nontender, and ulcerated lesions.Edema may concern only the lesion site or the entire vulva, depending on the size of the lesion.
If not recognized and consequently not adequately treated, it can extend so much that it subverts and destroys the anatomy of the vulva and perineum.

Results
In our review, fifty-four cases of vulvar lymphoma were reported in Table 1, with a median age of 50 years (range: 13-89).The most common anatomical site of interest was the vulva, although there are cases also involving the perineum, buttocks, and vagina.The mean lesion size at the time of treatment was 6 cm (data available for 23 cases, range 1.0-20.0cm).Vulvar lymphoma has usually been described as a mass, with or without ulceration, and it has rarely been associated with pain, in only one case with fever, more frequently with discomfort in a growing mass.
Literature analysis and data in Table 1 confirm the good prognosis of this disease.In fact, the patients who survived, in variable periods of observation, were 27/54 (50%), and only 8/54 (14.8%) died of disease, while 2/54 (3.7%) died of other causes and 3/54 (5.5%) of unknown causes.We have no follow-up data for 14/54 patients (26%).

Data Discussion
Patients with vulvar lymphoma are generally elderly (the mean age is about 60 years, range: 43-71 years) [33], and the classical manifestation of the disease is a vulvar mass.
On a histological level, B-cell lymphomas are the predominant type, whereas only a few cases of T-cell lymphoma have been described.The most common type is mycosis fungoides, although it occurs as a secondary involvement of the vulva in patients affected by NHL [33].
Although vulvar lymphomas usually affect the major or minor labia, two cases have been found in the Bartholin's gland: one secondary, described by Plouffe, with Bartholin's gland involvement by primary diffuse histiocytic lymphoma, found in the right breast, and one primary, described by Tjalma, considered the first case in the literature of primary diffuse large B-cell non-Hodgkin lymphoma involving the Bartholin's gland) [21,35].Ferrando-Marco reported one primary malignant large cleaved cell vulvar lymphoma, predominantly involving the clitoris, in a 60-year-old woman [27].
Martorell [37] described the case of an elderly woman with a lymphoma-like lesion of the left major labia, which, 7 years after diagnosis, transformed into a marginal zone B-cell lymphoma (lymphoplasmacytic lymphoma).In contrast with the other two studies in the literature, no correlation emerged with Epstein-Barr virus/Borrelia burgdorferi infection, as PCR detection of Borrelia burgdorferi and Epstein-Barr virus DNA was negative.This emerged even though marginal zone B-cell lymphoma has usually been associated with the use of drugs, such as fluoxetine and amitriptyline, which can alter the activity of the lymphoid system.El Kacemi [43] described the only case of primary NHL in a young immunocompetent woman.All the other cases in the literature involved patients who were immuno-deficient (e.g., with iatrogenic immunosuppression after allograft or with HIV infection) [30,31,54].
Even though Winnicki [38] described a case of vulvar T-cell HL of the vulva in a patient with Crohn's disease, a significant increase in the incidence of vulvar lymphoma has not been detected in patients with inflammatory bowel disease.Despite this case report, Hodgkin lymphoma in patients with Crohn's disease remains rare and most commonly affects the intestine [55][56][57].So far, no clear link between Crohn's disease and Hodgkin lymphoma has been found in any study; conversely, Palli, in his population-based study, demonstrated a correlation with an increased risk of ulcerative colitis [58].Buras [42] described, in a 50-year-old woman, the first case of primary mycosis fungoides of the vulva.Flow cytometry analysis revealed a predominant T-cell (CD2+, CD3+, CD5+) population that expressed CD4 and was negative for CD8.Immunohistochemical analysis revealed a T-cell population that was negative for natural killer cell markers.There was a minor lymphoid component in the lesion that was positive for CD20, a B-cell marker.
Recently, Dashraath [48] observed a rare cutaneous γ/δ T-cell subtype lymphoma in an elderly patient with diabetes.
Zizi-Sermpetzoglou [40] described the case of a 48-year-old woman who presented with primary intravascular vulvar lymphoma of T-cell origin and CD30 positive, while Morse [49] recently disclosed a case of a 64-year-old woman with aggressive primitive epidermotropic cytotoxic T-cell lymphoma, successfully treated with RT.

Immunophenotypic and Molecular Profiling
Histopathological classification and molecular profiling are essential for the diagnosis and treatment of lymphomas.
The use of immunohistochemistry and molecular genetic analyses makes it possible to distinguish between lymphoma, rhabdomyosarcoma, Ewing's sarcoma/peripheral neuroectodermal tumor (PNET), and Merkel cell tumor, an aggressive neoplasm of skin, which may rarely occur on the vulva [45].
In addition, reactive vulvar processes usually manifest as surface-extension, band-like, and non-infiltrating and commonly have a polymorphous population of lymphocytes, plasma cells, and histiocytes without atypia.
The hematoxylin-eosin-stained histologic sections of the vulvar masses' biopsy showed diffuse lymphomatous infiltrate cells with round nuclear contours, dispersed chromatin, small nucleoli, and scant cytoplasm.There were numerous mitotic figures and apoptotic bodies, and there were scattered "tingible body" macrophages containing nuclear and other cell debris dispersed amongst the tumor cells, leading to a starry-sky appearance [45,54].The presence or absence of fibrosis, necrosis, granulomas, and variations in cell morphology should also be noted.
From a morphologic standpoint, DLBCL is defined as a diffuse growth of neoplastic large B lymphoid cells that have a nuclear size equal to or exceeding normal macrophage nuclei, with prominent central nucleoli or smaller nucleoli, or obviously anaplastic.
Gene expression profiling has identified two major distinct forms of DLBCL depending on the cell-of-origin (COO): the germinal center B-cell (GCBC-) and the activated B-cell (ABC-) types.The former appears to derive from germinal center B cells, while the latter may derive from a post-germinal center B-cell (COO).ABC-DLBCL, which was associated with increased nuclear factor kB activity in the kB NF-kB chain, is characterized by more aggressive behavior and a worse prognosis than GBC DBCL [59][60][61][62].
Consequently, distinguishing between ABC and GBC DLBCLs is of clinical importance because, while the majority of patients with GCB-DLBCL respond well to standard R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) regimen chemotherapy, patients with ABC-DLBCL have a poorer prognosis.
More recently, studies on the role of key gene mutations and gene pathways helped to elucidate molecular mechanisms of lymphoma development and provided new prognostic tools to the clinician [65].
One clear example is the role of MYC alterations.Indeed, MYC rearrangements were found in 5% to 15% of DLBCLs and NOS often showed up with BCL2 or, less frequently, with BCL6 translocation [66,67].Transcription factor TCF3 or its negative regulator ID3 was associated with mutations in approximately 70% of sporadic and immunodeficient-related Burkitt lymphoma [68][69][70][71].
More recent studies highlighted JAK/STAT pathway mutations in several T-cell and NK-cell tumors.The importance of these anomalies lies in their correlation with the lymphomagenesis process, with the precise identification of the disease and its clinical severity, and with the possibility of setting up targeted therapies [65,[72][73][74][75].

Instrumental Investigations
The diagnosis of lymphomas, including the vulvar, makes use of the molecular identification of cellular strains that determine the disease.Biopsy findings indicate the type of vulvar lymphoma and appropriate approaches, from instrumental investigations to treatment.
Imaging studies play a major role in diagnosis, disease staging, and follow-up.Chest, abdomen, and pelvis CT scan or MRI are required for vulvar lymphoma staging, according to the Ann Arbor classification system and the IPI (International Prognostic Index) [76,77].Bone marrow biopsy may also be useful in staging and in differentiating primary from secondary forms.In conjunction with it, positron emission tomography (PET) imaging aids in correctly staging the disease.In fact, PET/CT is more accurate and sensitive than CT scans in identifying lymph nodes and extranodal localizations.PET-CT and MRI indicate more precisely whether surgery is appropriate.Basal CT, PET-CT, and MRI imaging play a key role not only in defining the disease stage at diagnosis and in providing baseline measurements for comparison purposes but also in setting and evaluating the treatment response.
It is interesting to note that the end-of-treatment PET complete response is highly predictive of progression-free survival and overall survival in DLBCL after first line immunochemotherapy.The suspicion of lymphoma is particularly strong when one or more solid, well-defined, homogeneous masses are displayed without necrosis, regardless of size or diffuse infiltration with architectural preservation.In addition, pelvic lymphadenopathy may be evident [78].Lymphoma density on CT scans is similar to moderately hypoattenuated muscles when compared with the surrounding parenchyma but more attenuated than water.
On MRI, lymphomas usually show low-to-intermediate signal intensity on T1-weighted imaging and moderately high signal intensity on T2-weighted imaging.
On PET, a standardized uptake value greater than 2.5 suggests malignancy [78].PET imaging, in combination with bone marrow biopsy, contributes to the correct staging of disease.Basal imaging serves both to define the disease stage at diagnosis and to provide baseline measurements for comparison to evaluate treatment response.

Treatment
If the rarity of primary and secondary vulvar lymphomas is considered, there is currently no consensus on the treatment.Consequently, patients are initially treated for any other common gynecologic malignancy, and treatment is fundamentally based on the surgical and radio/chemotherapy approach.In clinical practice, the treatment decision is also determined based on various factors such as the stage, age, presence of bulky disease, performance status, and International Prognostic Index (IPI).IPI is the most commonly used model for predicting survival in aggressive lymphoma.
Vulvar NHL has a good prognosis, and a complete cure has been demonstrated.Indeed, NHLs are generally highly responsive to radio-chemotherapy; thus, surgery is not the primary choice of therapy for vulvar lymphoma.
For early stage I and II disease, radiotherapy alone is suitable, providing good overall results.The dose range varies from 30 to 40 Gy in 3-4 weeks [43,79].For advanced stage III and IV disease, the most frequent approach consists of 4-6 cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy, with or without radiotherapy consolidation.This treatment is particularly indicated, as it achieved a 60-70% complete response rate [6].Therefore, chemotherapy produces approximately the majority remission rate, but relapse of the disease, even after complete remission, is not unusual in these highly malignant forms, especially in the central nervous system.When these relapses occur, the outcome will be fatal.
R-CHOP appears more effective in patients with GCB-DLBCL than with ABC-DLBCL.In the latter setting, radiotherapy may improve response.
Finally, radiotherapy can be administered with a symptomatic, palliative aim or in the management of aggressive cutaneous vulvar lymphomas, as the vulvar primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma was reported to be highly responsive to radiation therapy [49].

Conclusions
Although vulvar lymphoma has been reported to involve the female genital tract, vulvar localization remains extremely rare.Hodgkin lymphomas (HLs), with their classical and non-classical sub-types, represent the minor component, while the majority are identified as non-Hodgkin lymphomas (NHLs), which include B-cell, T-cell, and natural killer (NK) cell types.
Primary vulvar lymphomas usually present as a fast-growing, nontender, and ulcerated vulvar mass, often associated with nonspecific symptoms such as itching, swelling, itching, burning, discomfort, or pain, usually associated with edema that may involve only the lesion site or the entire vulva.They are aggressive and, from a pathological point of view, are most often DLBCLs.
Diagnosis requires biopsy, and management may involve a combination of surgery, radiotherapy, and chemotherapy.Since vulvar lymphomas are rare tumors, management by a multidisciplinary team is highly recommended, and experts in hematological diseases should be involved in disease management.

Figure 1 .
Figure 1.Study flow schema: PRISMA flow diagram of the process of identification, screening, and inclusion of articles.Systematic literature reviews were selected, using standard methods to be briefly presented in the article.

Figure 1 .
Figure 1.Study flow schema: PRISMA flow diagram of the process of identification, screening, and inclusion of articles.Systematic literature reviews were selected, using standard methods to be briefly presented in the article.

Table 1 .
Lymphomas of the vulva: main clinical and pathological features reported in the literature.