Diagnostic utility of programmed cell death ligand 1 (clone SP142) in mediastinal composite lymphoma: A report of two cases

Abstract

Composite lymphoma is a well‐known diagnostic entity exhibiting the synchronous occurrence of two or more distinct types of lymphomas in the same specimen. Here we report two patients, a 14‐year‐old female (Case 1) and a 45‐year‐old male (Case 2), with mediastinal composite lymphoma, comprising nodular sclerosis classic Hodgkin lymphoma (NSCHL) and primary mediastinal large B‐cell lymphoma (PMBL). Both patients had a mediastinal mass, and manifested two different histologic components in the same biopsy, one characteristic of NSCHL and the other PMBL. The NSCHL areas included Hodgkin and Reed–Sternberg (HRS) cells with typical immunophenotypic features (CD30‐positive and CD20‐negative), whereas the sheets of large tumor cells characteristic of PMBL were strongly and uniformly CD20‐positive. Interestingly, although both cases showed neoplastic PD‐L1 (nPD‐L1) positivity on the HRS cells of NSCHL, they differed regarding nPD‐L1 expression on the PMBL tumor cells. In Case 1, the nPD‐L1‐negative PMBL component was anatomically situated outside the NSCHL lesion. On the other hand, in Case 2, the nPD‐L1‐positive PMBL component was characterized by transitional or continuous areas with the NSCHL component. These findings suggested that nPD‐L1 expression may define two subtypes of PMBL that are more similar to or distinct from classic Hodgkin lymphoma.

Diagnostic utility of programmed cell death ligand 1 (clone SP142) immunohistochemistry for malignant lymphoma and lymphoproliferative disorders: A brief review

“…48,49 Among reported series, nPD-L1 expression was variable in PMBL with different PD-L1 clones and cohorts, ranging from 29% to 100%, 9,14,[50][51][52][53] suggesting the presence of nPD-L1-positive and -negative subgroups of this distinct lymphoma. Accordingly, among our Japanese patients, nPD-L1 expression was observed in 100% with mediastinal NSCHL (n = 7) and 18% with PMBL (n = 11), 54 the latter being similar (15%) to another Japanese series. 48 However, these rates may be lower than in Western populations, possibly because of the relative paucity (approximately one-third) of these mediastinal diseases in Asia.…”

“…48 However, these rates may be lower than in Western populations, possibly because of the relative paucity (approximately one-third) of these mediastinal diseases in Asia. 55 We recently reported nPD-L1 expression and its correlation with pathological findings (i.e., anatomical position) in two cases of mediastinal composite lymphoma, one with nPD-L1-positive PMBL (Figure 2A, 2B) and the other with nPD-L1-negative PMBL components, 54 which may provide additional support to the assertion of the two distinct subtypes of PMBL being closer to and more distinct from CHL, respectively.…”

Hodgkin Lymphoma: Biology and Differential Diagnostic Problem

“…Our group has demonstrated that PD-L1 expression was more frequently observed in CHL than PMBL (100% vs. 18%), when using clone SP142 [ 125 ]. Seven NSCHL cases were positive for PD-L1, while only two out of 11 PMBL were positive for PD-L1.…”

“…Seven NSCHL cases were positive for PD-L1, while only two out of 11 PMBL were positive for PD-L1. Notably, these PD-L1-positive PMBL cases were accompanied by a relatively rich inflammatory background, with a moderate number of small lymphocytes, and/or sclerotic changes, with difficulties to differentiate from MGZL [ 125 ]. Using the same antibody clone, a study by the Lymphoma Study Association (LYSA) also showed that neoplastic PD-L1 expression was more frequently observed in CHL than in MGZL (80% vs. 54%) [ 126 ].…”

Composite lymphoma of cervical lymph nodes with classical Hodgkin lymphoma and diffuse large B cell lymphoma: a case report and literature review

“…CL is rarely described in literature, and its description has been limited to isolated case reports (9)(10)(11)(12). However, its incidence may be underestimated as sophisticated techniques are required in the diagnosis of CL, and, due to its inconsistent definitions, the incidence of CL reported across different studies varies (13).…”