Cutaneous localization of angioimmunoblastic T‐cell lymphoma may masquerade as B‐cell lymphoma or classical Hodgkin lymphoma: A histologic diagnostic pitfall

Abstract

Background We report the cases of three patients presenting skin lesions whose biopsies showed nodular polymorphic infiltrates consisting of lymphocytes, plasma cells, histiocytes, eosinophils, B blasts, and Hodgkin Reed‐Sternberg (HRS)‐like cells. Two of them were initially diagnosed as classical Hodgkin lymphoma (cHL), on the other hand, the last one as a B‐cell lymphoma. All patients have been treated for angioimmunoblastic T‐cell lymphoma (AITL). Methods We performed a second review of the skin biopsies with further immunophenotypic molecular analyses. Scrupulous observation revealed, in the background of the three cases, atypical small to medium‐sized lymphocytes carrying a CD3+, CD4+ T‐cell phenotype and expressing PD1 and CXCL13 follicular helper T‐cell markers. The two lesions initially diagnosed as cHL showed scattered HRS‐like cells with CD30+, CD15+, PAX5+, CD20−, Epstein Barr Virus (EBV) + classical phenotype. The case initially diagnosed as B‐cell lymphoma showed a diffuse B‐cell proliferation associated with small B‐cell and medium to large‐sized B blasts that were positive for EBV. Conclusion Those cases highlighted that atypical T‐cells may be obscured by B‐cell proliferation mimicking cHL or B‐cell lymphoma in cutaneous localization of AITL and confirmed the requirement of collecting clinical information before performing a diagnosis.

Hodgkin Reed–Sternberg-Like Cells in Non-Hodgkin Lymphoma

“…Skin biopsies show dermal infiltrate of CD20− and EBER-positive medium-to large-sized atypical lymphoid cells hiding neoplastic T cells [76]. The RSLCs are positive for CD30, CD15, and EBV, and have a partially preserved B cell program (focal and weak PAX5 positivity, CD20 negativity) as described in cHL [76]. Although skin occurrence of cHL is rare, it has been described in advanced stages with the same clinical skin damages as cutaneous AITL [79].…”

“…Patients with cutaneous involvement classically present a transient morbilliform eruption or other cutaneous manifestations such as papules, nodules, urticarial plaques, and erythroderma [75]. EBV infected B cell expansion is typically observed in AITL [76].…”

“…Prominent granulomatous reaction may also be observed, sometimes mimicking infectious lesions [78]. Other patterns are suggestive of cutaneous lymphoma and may present as sparse superficial perivascular or dense pleomorphic infiltrate with atypical lymphocytes [75,76]. Due to the scarcity of neoplastic T cells, establishing a diagnosis of AITL may be challenging in cutaneous lesions [76].…”

Diagnostic Considerations in the Evaluation of Large B-Cells on Lymph Node Cytology Specimens

“…Histologic evaluation of lymph node excisions typically reveals a mixed inflammatory infiltrate composed of small lymphocytes, plasma cells, macrophages, eosinophils, immunoblasts, and Reed-Sternberg-like cells admixed with a relatively small proportion of small-to-medium-sized malignant T-cells [14]. Abnormal B-cell expansions with large immunoblastic morphology in cases of AITL have previously been described and can lead to misclassification of lymphomas as DLBCL or Hodgkin lymphoma on histologic evaluation [15, 16] but has not been previously discussed in the evaluation of cytologic specimens. Notably, these larger B-cells are polytypic and EBV positive.…”

Lymphomatoid papulosis mimicking relapsed angioimmunoblastic T‐cell lymphoma on histology: the importance of clinicopathological correlation

“…Nodular/ulcerating skin involvement is unusual in AITL (which typically presents as a macular-papular rash) and may suggest secondary B-cell proliferation. 5 In this context, the aberrant coexpression of CD20 that was observed may be misleading. The lack of expression of other B-cell markers and the expression of pan T-cell antigens pointed to a T-cell LPD.…”