Background/Purpose:

 The risk of malignancy in patients with Granulomatosis with
Polyangiitis (GPA) is increased, as shown in several previous studies. The risk
of lymphoma has been described as high as 4-5-fold increased. In addition,
lymphoma in the sinonasal region, especially NK/T-cell lymphoma, has been
reported to mimic GPA localized to the ear-throat-nose (ENT) region. Several
previous publications report cases where a sinonasal lymphoma initially was
misdiagnosed as GPA. We therefore had a particular interest in investigating
the presence of lymphoma localized in the ENT-region. Our aim in this study was
to assess the clinical characteristics and treatment of patients with GPA
complicated by lymphoma and to describe the lymphoma types, sites and prognosis
in a population-based setting.

Methods:

From
the Swedish population based patient register all individuals with a diagnosis
of GPA between 1964 and 2012 were identified (n=3,224). Through linkage with
the Swedish cancer register all lymphoproliferative malignancies (ICD7:200-202)
registered after the first discharge listing GPA were identified. The medical
records of all patients with GPA and lymphoma were collected and the GPA
diagnosis was evaluated using the EMEA Consensus Algorithm for Classification
of Vasculitis (1). To confirm the lymphoma diagnosis all lymphoma tissues were
retrieved and classified according to the latest WHO classification. Clinical
data of both GPA and lymphoma were collected from the medical files.

Results:

In
all, 24 GPA-patients with malignant lymphoma were identified. 20 of these were
B-cell lymphomas, and only two T-cell lymphomas (Table). Only one of the
lymphomas was localized to the ENT-area, a diffuse large B-cell lymphoma in the
hard palate. The majority of the patients had generalized GPA disease, most
(75%) had been treated with cyclophosphamide for their GPA, many for long periods
and with high doses; the median cumulative dose was 40g. The mean time from GPA
to lymphoma diagnosis was 10 years (0-22). The majority of the lymphomas were
aggressive and the median survival after lymphoma diagnosis was only 4 months.

Conclusion:

The findings
in this population-based setting indicate that the lymphomas developing in
patients with GPA are aggressive with a poor prognosis. T-cell lymphoma or
lymphoma localized to the ENT-area are not a prominent finding. The study
emphasizes the need for awareness of lymphoma and long-term follow-up of
patients with GPA.

1. Watts, R et al. Ann Rheum
Dis, 2007