Cutaneous reactive lymphoid proliferation (CRLP) is a condition that resembles cutaneous lymphoma, and differentiating the two is necessary for proper diagnosis and treatment. It can be idiopathic or caused by viruses, drugs, or skin trauma, resulting in reactive lymphoid hyperplasia. Several clinical and histopathological features are helpful for differentiating CRLP from lymphoma, and they must be considered as a whole to reach the correct diagnosis. The number, location, and progression of CRLP lesions are important clinical clues, while the type, size, arrangement, surface markers, and clonality of the cellular infiltrate are key histopathological clues. We present a case in which CRLP arose in the setting of concomitant antidepressant and antihypertensive use, which are both potential causes of CRLP. In this case, excision served as both diagnosis and treatment. The benign presentation and lack of clonality led to the diagnosis of CRLP. While the cause is unknown, drug exposure was a possible inciting factor, and the patient will be monitored for recurrence.

We report a case of reactive lymphoid hyperplasia (RLH) mimicking colorectal liver metastases (CRLM) on preoperative workup that was clinically indistinguishable. A 78-year-old woman was found to have locally-advanced sigmoid cancer (T4), and then treated with radical sigmoidectomy. One year after the surgery, plain computed tomography (CT) revealed a low-density area in the right hepatic lobe. Metastatic liver tumors could not be ruled out with CT/ magnetic resonant imaging (MRI) and positron emission tomography-CT . Based on these findings, the patient was diagnosed with CRLM at S7 of the liver. The patient underwent right posterior sectionectomy. The tumor was adjacent to the right hepatic vein; however, no invasion was observed. The patient was pathologically diagnosed as having RLH. The patient showed no signs of recurrence 16 months after initial surgery. RLH is clinically indistinguishable from CRLM. Further evaluation is required to elucidate the effective strategies of detecting and treating hepatic RLH.

A 53-year-old female with primary biliary cholangitis was referred for the evaluation of a hepatic nodule identified during routine imaging. Ultrasonography revealed a homogeneous, hypoechoic, 18 mm nodule in segment 3 of the liver. On dynamic CT and MRI, the nodule showed mild enhancement at the hepatic artery-dominant phase. On diffusion-weighted images, the nodule exhibited pronounced hyperintensity with accompanying wedge-shaped perinodular hyperintensity (comet and comet-tail appearance). The nodule showed a portal perfusion defect on CT during arterial portography, and mild enhancement on CT during hepatic arteriography (CTHA). A nodular and wedge-shaped perinodular enhancement (comet and comet-tail appearance) in the CTHA was also clearly observed. The nodule demonstrated abnormal FDG uptake on 18F-FDG-PET/CT. An excisional biopsy was performed for histopathological diagnosis, and the nodule was diagnosed as reactive lymphoid hyperplasia (RLH). Diagnosing hepatic RLH by imaging is challenging due to its imaging findings overlapping with those of various malignant tumors, especially the nodular type of lymphomas, making differentiation particularly difficult. However, radiologists should note the perinodular early enhancement and the perinodular hyperintensity on diffusion weighted images, which are thought to be key imaging findings of RLH, along with other characteristics such as a single, small, homogeneous nodule with mild early enhancement and marked restricted diffusion. We propose to name the nodular lesion with perinodular early enhancement/hyperintensity on diffusion weighted images as \'comet and comet-tail appearances\'.

Lymph node biopsy is indicated in patients with suspected malignancy or lymphadenopathy due to unclarified reasons. Lymph node biopsy can be performed as fine needle aspiration biopsy, core biopsy, or excisional lymph node biopsy. In particular, the diagnosis of malignant lymphoma is considered insufficient for oncological treatment unless classified into subgroups. Core biopsy and excisional biopsy can be performed to diagnose lymphoma and classify it into subgroups. Core biopsy may also be limited in some cases for the diagnosis of lymphoma. Therefore, patients are referred to surgical departments for excisional lymph node biopsy. It was aimed herein to analyze the results of excisional lymph node biopsies performed for diagnostic purposes in our department. Data on 73 patients having undergone diagnostic excisional lymph node biopsy at Sakarya University Medical Faculty Training and Research Hospital between January 2008 and January 2020 were retrospectively analyzed. Patients were evaluated in terms of age, gender, biopsy site, pathological diagnosis, number and diameter of lymph nodes excised. Patients younger than 18 years of age, those with sentinel lymph node biopsies, and lymph node dissections performed for any known malignancy were excluded from the study. Statistical data analysis was done using SPSS statistical software. There were 37 (50.7%) female and 36 (49.3%) male patients, mean age 52.07 (18-90) years. Axillary lymph node biopsy was performed in 32 patients, inguinal lymph node biopsy in 29 patients, cervical lymph node biopsy in 3 patients, intra-abdominal lymph node biopsy in 6 patients, mediastinal lymph node biopsy in 1 patient, and supraclavicular lymph node biopsy in 2 patients. All of the lymph node biopsies were performed as excisional biopsy. Malignancy was detected in 36 (49.3%) patients. In 37 (50.3%) patients, the causes of lymphadenopathy were found to be benign pathologies. When the causes of malignant disease were examined, it was observed that 23 (31.5%) patients were diagnosed with lymphoma. Hodgkin lymphoma was detected in 5 patients diagnosed with lymphoma, and non-Hodgkin lymphoma was found in 18 patients. Metastatic lymphadenopathy was observed in 13 (17.8%) patients. Reactive lymphoid hyperplasia (26%) and lymphadenitis (20.5%) were found among the causes of benign lymphadenopathy. The number of excised lymph nodes was between 1 and 4, and their diameter was between 9 and 75 mm (mean: 29.53±15.56 mm). There was no statistically significant difference between benign and malignant patients according to gender, age, lymph node diameter, number of lymph nodes excised, and excisional lymph node biopsy site. For diagnostic lymph node biopsy, fine-needle aspiration biopsy and core biopsy should be performed primarily. If lymphoma is suspected in the diagnosis, fine-needle aspiration biopsy is not necessary. In this case, it is believed that it is more appropriate to perform core biopsy first. If the core biopsy is insufficient for diagnosis, it is more appropriate to perform surgical biopsy in order to cause no delay in diagnosis and treatment. Excisional biopsy is a method that can be safely performed and does not cause severe morbidity in palpable peripheral lymphadenopathies. Although it does not cause severe morbidity because it is an invasive procedure, excisional biopsy should be performed in a selected patient group.

Reactive lymphoid hyperplasia (RLH) of the liver is extremely rare. Despite advancements in diagnostic imaging technology, it is still difficult to distinguish from hepatocellular carcinoma (HCC). Herein, we present a case of hepatic RLH mimicking HCC that was postoperatively diagnosed using several imaging modalities. A 78-year-old female was referred to our hospital with a positive hepatitis C virus antibody (HCV Ab) test. Ultrasonography revealed a 13 mm isoechoic lesion in segment 8 of the liver. Contrast-enhanced computed tomography (CE-CT) demonstrated arterial hyperintensity and washout during the later phase. On ethoxybenzyl magnetic resonance imaging (EOB-MRI), the lesion was hyperenhanced in the arterial phase and of low intensity in the hepatocyte phase. Although the tumor markers were all within normal limits, the pattern of contrast enhancement of the tumor on CT and MRI was consistent with that of HCC. We performed S8 segmentectomy of the liver. Histological examination of the resected specimen revealed dense lymphoid tissue of variable sizes and shapes with expanded germinal centers. Immunohistochemical examination was positive for CD3, CD10 (germinal center), and CD20, and negative for B-cell lymphoma 2 (bcl-2) (germinal center) and Epstein-Barr virus (EBV). A polymerase chain reaction (PCR) analysis of IgH-gene rearrangements revealed polyclonality. Based on these findings, hepatic RLH was diagnosed. The postoperative course was uneventful, and the patient was discharged on the 10th postoperative day. She had a good quality of life after surgery and no liver nodule recurrence was detected at the 4-month medical follow-up. Hepatic RLH is an extremely rare disease and preoperative diagnosis is difficult. This should be considered in the differential diagnosis of single small hepatic tumors. An echo-guided biopsy and careful observation of imaging may help diagnose hepatic RLH, and a PCR analysis of IgH-gene rearrangements would be necessary for the definitive diagnosis of hepatic RLH.

Pseudolymphoma (PSL) of the orbit is a benign lymphoid hyperplasia (LH). It is a rare disease with an extensive range of known causative agents. LH is further classified into \"reactive\" (RLH) and \"atypical\" (ALH) types. It clinically presents as a single or a few plaques and/or nodular lesions, particularly on the head, neck, and upper trunk. It must be differentiated from orbital malignant lymphoma. In this report, we present a case of a 58-year-old Pakistani female with an asymptomatic recurrent right periorbital swelling for three years. It was clinically diagnosed as an angiotensin-converting enzyme (ACE) inhibitor-induced angioedema as it responded to stopping the ACE inhibitor; however, after four months, the patient again started to develop right periorbital swelling. An incisional biopsy revealed perivascular and periadnexal infiltration of lymphocytes, plasma cells, and a few neutrophils along with pigmentary incontinence. The formation of multiple lymphoid follicles and infiltration by monomorphic lymphoid cells in deeper skeletal muscle fibers were also observed. Immunohistochemistry (IHC) showed polyclonality and low Ki-67 labeling (20%), corresponding to periorbital RLH. Our objective in this study is to highlight the importance of considering PSL as a differential diagnosis in periorbital swelling. We also suggest that recurrent angioedema may lead to PSL.

Reactive lymphoid hyperplasia (RLH) of the liver is a rare benign disease. This article describes a 77-year-old female patient with RLH of the liver. The patient was admitted to the hospital due to atrial fibrillation. A liver tumor was incidentally found during abdominal enhanced CT. Further magnetic resonance imaging (MRI) and PET/CT showed four lesions in the liver. The imaging findings suggested hepatocellular carcinoma (HCC), but it was not consistent that the patient had no history of liver cirrhosis and hepatitis, and a variety of tumor markers were within the normal range. The largest lesion was surgically removed and microscopically diagnosed as RLH of the liver. The pathology included a large number of reactive hyperplastic lymphoid follicles. Immunohistochemical examination showed that the infiltrating lymphocytes were polyclonal. The authors believe that the perinodular enhancement on MRI, the obvious limitation of diffusion on DWI, the insignificant increase of SUVmax on PET-CT delayed phase, and the support of clinical data can help distinguish liver RLH from lymphoma and HCC.

Pulmonary nodular lymphoid hyperplasia is a rare, nonneoplastic lymphoproliferative disorder mostly manifesting as one or more nodules or localized lung infiltrates. The lesion comprises reactive germinal centers with well-preserved mantle zones and sheets of interfollicular mature plasma cells, lymphocytes, histiocytes, and neutrophils. The radiological finding is not specific, and the diagnosis of pulmonary nodular lymphoid hyperplasia relies generally on pathohistological and immunohistochemical analyses. The most important differential diagnoses are extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue and immunoglobulin G4-related sclerosing disease. Nonetheless, we present a case of pulmonary nodular lymphoid hyperplasia in a 69-year-old woman with the diagnostic challenge of cytological atypia in alveolar spaces inside the lymphoid tissue, coexisting with the diagnosis of adenocarcinoma of the lepidic pattern. Therefore, this case highlights the importance of identifying these rare benign and reactive lymphoproliferative diseases given the risk of developing not only lymphoma but also carcinoma.

BACKGROUND: Histopathological characteristics of cytomegalovirus (CMV) lymphadenitis have been well described. Rare studies have reported the immune status and clinical features. Clinically, experts believed that CMV lymphadenitis develops in immunocompromised and immunocompetent patients. Infectious mononucleosis (IM)-like syndrome is the most well-known clinical presentation.
METHODS: We reviewed archived CMV immunohistochemical stains on lymphoid tissues. The clinicopathological features of CMV-positive cases were studied.
RESULTS: For lymph nodes, we detected CMV in 29% (5/17) allogeneic peripheral blood hematopoietic stem cell transplantation (PBSCT) recipients, 29% (4/14) post-autologous PBSCT patients, 13% (6/47) patients treated with intravenous chemotherapy, and 9% (9/96) immunocompetent patients. We detected CMV in 7% (2/24) of tonsils but not in the nasopharynx, tongue base, or spleen specimens. The patients with iatrogenic immunodeficiency ranged from 37 to 76 years old. CMV infections developed a few years after lymphoma treatment (median duration after allogeneic PBSCT, 932 days; after autologous PBSCT, 370 days; and after chemotherapy, 626 days). The most common clinical presentation was neck mass (13/25, 42%), followed by asymptomatic image finding (10/25, 40%). Positron emission tomography/computed tomography (PET/CT) scan showed increased uptake compared to the liver in all patients (11/11, 100%). Of 10 lymphoma patients, 8 (80%) had a Deauville score of 4-5; they accounted for 30% (8/27) of lymphoma patients with false-positive PET/CT scan results. All cases were self-limiting. 96% (23/25) cases had Epstein-Barr virus coinfection, and EBER-positive cells were predominantly in a few germinal centers.
CONCLUSIONS: Cytomegalovirus (CMV) lymphadenitis and tonsillitis were subclinical infections, not primary CMV infection with IM-like syndrome. The lymphadenopathy typically developed a few years after lymphoma treatments in the middle-aged and the elderly. The lesions mimicked lymphoma relapse in PET scans. Therefore, recognizing CMV infection in lymphoid tissues is of clinical importance.

BACKGROUND: Reactive lymphoid hyperplasia (RLH) of the liver is a rare liver lesion. It is considered difficult to differentiate radiologically from hepatocellular carcinoma, metastatic liver tumor and other pathologies.
METHODS: A 54-year-old woman presented to our hospital with RLH of the liver. The patient had a diagnosis of metastatic carcinoma of the liver from an unknown origin and subsequently underwent partial hepatectomy. However, histopathological analysis revealed RLH. The lesion showed perinodular enhancement in the arterial phase on contrast-enhanced computed tomography and magnetic resonance imaging. On diffusion-weighted imaging (DWI), we encountered linear hyperintensity along the portal tract consecutive to the liver lesion, which is a new characteristic radiologic finding. This finding corresponded to the lymphoid cell infiltration of the portal tract. Furthermore, there was strongly restricted diffusion on the apparent diffusion coefficient map. We used these characteristic radiologic findings to diagnose the lesion as a lymphoproliferative disease.
CONCLUSIONS: The linear hyperintensity consecutive to the liver lesion on DWI provided additional valuable diagnostic information.