LAUSR

Dear Editor, Progressive transformation of germinal centers (PTGC) is a common, but often underdiagnosed cause of benign peripheral lymphadenopathy that is characterized by reactive follicular hyperplasia along with mantle zone lymphocyte expansion into the adjacent sinusoids and germinal centers (GC); the follicles with GC become enlarged and replaced by small lymphocytes from the mantle zone (mainly B cells) [1]. This entity can precede, appear during or after Hodgkin’s lymphoma (HL), mainly nodular lymphocyte predominant Hodgkin’s lymphoma (NLPHL) [2]. The disease itself can also be wrongly diagnosed as early stage NLPHL or follicular lymphoma (FL); therefore, new immunoarchitectural patterns to distinguish between these entities have recently been proposed [1, 2]. We have presented two cases of PTGC along with visual illustrations of the clinical and pathological characteristics. A 32-year-old male presented with painless submandibular and cervical lymphadenopathy. It is worth noting that the patient was under oncological surveillance after a radical distal pancreatectomy due to neuroendocrine pancreatic cancer pT2N0M0 4 years earlier. Upon physical examination, we found enlarged lymph nodes level I, II, and III. Laboratory tests were irrelevant, apart from erythrocyte sedimentation rate (ESR) 22 mm/1 h (1–15) and beta-2-microglobulin 1.96 mg/L (0.7–1.8). We performed an ultrasound (Fig. 1a), which showed hypoechoic, enlarged (to 24 × 20 mm) lymph nodes without visible hilus, one on which a fine needle aspirational biopsy (FNAB) was done. The results of cytopathology were inconclusive—immunohistochemistry (IHC) staining confirmed LCA (+) and CD56 (−), so our further task was to differentiate between reactive lymphadenopathy and low-grade lymphoma. Due to the patient’s history and a suspicion of lymphoma, a PET-CT with FDG was ordered; it revealed an increased uptake of the radiotracer (SUVmax up to 8.9) among many of the cervical lymph nodes (Fig. 1b). Afterwards, a surgical excisional biopsy was done and showed giant, irregular shaped germinal centers with further IHC that confirmed the diagnosis of PTGC. A 65-year-old female presented with a single, painless mass in the submandibular region. The patient was under gastroenterological observation due to primary sclerosing cholangitis and silent coeliac disease. Upon examination, the patient had an enlarged, round, and well-shaped submandibular lesion. An otorhinolaryngology examination did not reveal further findings that would suggest the cause of the lymphadenopathy. Laboratory tests were also irrelevant, apart from elevated beta-2-microglobulin 2.02 mg/L (0.7–1.8). On the ultrasound, we found a hypoechoic lymph node sized 10 × 17 mm with abundant vascularization. A FNAB of the lesion was performed and the cytopathology results suggested a reactive lymphadenopathy and advised a core biopsy in the case of further clinical doubts. A magnetic resonance was ordered to exclude other pathologic findings in the head and neck area. It showed enlarged submandibular (level IB) lymph node that displayed contrast enhancement (Fig. 1c). Due to the vague clinical symptoms and the patient’s preference for lesion removal rather than active surveillance, an excisional biopsy was done. The pathologic report suggested follicular lymphoid hyperplasia with PTGC (Fig. 1D1). The BCL2 (Fig. 1(D3)), BCL6 (Fig. 1(D2)), and CD10 expression was normal. PTGC is quite a common clinical entity that accounts for 3.5% of cases of chronic lymphadenitis [3]. The disease * Konrad Tałasiewicz [email protected]