Pathology of Primary Cutaneous Diffuse Large B-Cell Lymphoma
Syn: (According to WHO classification 2008 )- Primary Cutaneous Diffuse Large B-Cell Lymphoma, leg type
(According to WHO classification 2005 ) Primary cutaneous diffuse large B cell lymphoma, leg type and Primary Cutaneous Diffuse Large B-Cell Lymphoma, other.
Diffuse large B-cell lymphomas (DLBCL) are composed of variable proportions of centroblasts and centrocytes, although large cleaved, multilobulated and anaplastic cells may form part or all of the lesion. All cases of diffuse large B-cell lymphoma of the leg are included in this heading (WHO classification 2005 and 2008).
The small number of cases reported as T-cell rich large B-cell lymphoma are also best included in this group as occurs at other sites.
Most cases of Crosti’s reticulohistocytoma of the dorsum probably also fall within this category although some may represent primary cutaneous marginal zone B-cell lymphoma or primary cutaneous follicular lymphoma.
Diffuse large B-cell lymphomas on the head and trunk and have an excellent prognosis despite their diffuse large cell morphology with radiotherapy being the treatment of choice.
On the other hand diffuse large B-cell lymphomas of the leg occur in a more elderly population with female predominance, have a much higher relapse rate and more unfavourable long term survival, chemotherapy is the optimum treatment.
According to some pathologists, the behavior of a lymphoma is unlikely to be determined by whether it occurs above or below the waist.
They suggest that the poor prognosis of DLBCL of the leg is most likely related to the frequent presence of multiple lesions at presentation, and cite cases of DLBCL presenting with multiple lesions on the scalp and which have an equally aggressive clinical course.
Epstein-Barr virus is known to be associated with the development of lymphomas in immunosuppressed patients including diffuse large B-cell lymphoma.
Recently, age-related immune impairment was recognized as a predisposing factor in the development of Epstein-Barr virus-driven lymphoproliferative processes in elderly patients.
The proportion of EBV-related DLBCL cases in the elderly may be higher than that estimated at present.
Therefore, it was proposed by some authors that EBV expression should be assessed in primary cutaneous DLBCLs.
Primary Cutaneous Diffuse Large B-Cell Lymphoma arises on the trunks, head and neck and lower legs. The upper extremities seem to be rarely involved.
Most lesions present as tumours or papulonodules which may be surrounded by a slightly infiltrated erythematous halo, the later often preceding the development of the former.
Lesions on the upper body are frequently solitary or localised to a circumscribed area, where as those on the leg more often affect multiple discrete sites.
Despite a relatively high recurrence rate the prognosis is generally favourable with 5-year survival rates up to and in excess of 95% cases reported.
Radiotherapy is the treatment of choice for single/localized lesions on the head and trunk, whereas multiagent chemotherapy is preferred for multiple lesions at separate sites, whether or not these include the leg
Cases described as T-cell rich large B-cell lymphoma share the characteristic indolent behaviour of other Diffuse Large B-Cell Lymphoma limited to a single site.
Pathological Features: Dermatopathology Quiz Case 177
Most cases show a diffuse infiltrate extending from the upper dermis to subcutaneous fat, although early lesions may display a periadnexal and perivascular distribution superficially.
A grenz zone is usually present.
The infiltrate usually has a polymorphic appearance comprising an admixture of centroblasts, immunoblasts and large centrocyte-like (cleaved) cells, the former characteristically forming the majority.
Cells with multilobulated nuclei and anaplastic cells may also be present in varying numbers.
Lesions occurring on the leg are said to often have a monotonous appearance, consisting almost entirely of large round cells, either centroblasts or immunoblasts.
Macrophages are often present but eosinophils, neutrophils and plasma cells are not commonly seen.
Small T-cells may be present in large numbers in some cases, accounting for reports of cutaneous T-cell rich large B-cell lymphoma.
Immunohistochemical examination reveals that in all cases the neoplastic lymphocytes express CD20 and appear to lack CD5 and cyclin D1, although a significant proportion co-express CD10 and /or bcl-6. In a minority of cases CD43 and/or CD30 expression may be seen.
Bcl-2 positivity is seen in a variable number of cases. It has been proposed that bcl-2 expression is largely restricted to lesions occurring on the leg and that presence of the protein is associated with a poor prognosis.
Cases which can be reliably identified as possessing a diffuse large cell morphology in the literature uniformly lack t(14;18) when investigated by PCR, despite expression of CD10 or bcl-6.
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