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\'.

UNASSIGNED: Hepatic reactive lymphoid hyperplasia (RLH) is a rare benign lymphoproliferative lesion and a poorly understood disease. It is usually asymptomatic and incidental, but it is difficult to distinguish from hepatocellular carcinoma and metastatic liver tumor on imaging, and percutaneous biopsy is not sufficient to distinguish from low-grade malignant lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), making diagnosis difficult.
UNASSIGNED: A 69-year-old woman came to our hospital for reexamination of pulmonary nodules followed by liver occupation. The lesions showed \"wash-in and wash-out\" on contrast-enhanced ultrasonography and magnetic resonance imaging. Enhanced magnetic resonance also showed annular envelope enhancement and limited diffusion on the ADC map during the delay period. Imaging revealed metastatic liver cancer, and the patient underwent a partial hepatectomy. However, the final histopathological diagnosis was RLH.
UNASSIGNED: If small isolated nodules are found in the liver of middle-aged and elderly female patients with no risk factors for liver malignancy, when the enhanced imaging suggests \"wash-in and wash-out\", further focus should be placed on whether the enhanced imaging shows perinodular enhancement and whether the DWI shows limited diffusion in MRI, in order to emphasize the possibility of liver RLH diagnosis.

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.

BACKGROUND: Benign lymphoid hyperplasia (BLH) is a rare lymphoproliferative disorder of normal polyclonal B lymphocytes, but is sometimes difficult to distinguish from malignancy.
METHODS: An 87-year-old man with a history of localized non-small cell lung cancer (NSCLC) was referred for evaluation and treatment of an elastic hard tumor in the left supraclavicular fossa one year after stereotactic ablative radiotherapy (SABR). Whole-body PET scan showed high 18F-fluorodeoxyglucose uptake in the left supraclavicular fossa, and a dia-gnosis of oligometastasis was made. The tumor was homogeneously high signal on T2-weighted image with homogeneous enhancement after contrast administration. Since the palpation and MRI findings were inconsistent with those of metastatic NSCLC, a bio-psy was performed. Pathological and immunohistochemical investigation revealed the lesion to be BLH.
CONCLUSIONS: In a patient with suspected oligometastasis after SABR for NSCLC, caution should be exercised before undergoing SABR for oligometastasis because BLH may be present.

It is difficult to histologically differentiate extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) from chronic gastritis (CG)/ reactive lymphoid hyperplasia (RLH). To determine whether immunohistochemistry for IRTA1 and MNDA can differentiate gastric MALT lymphoma from CG/RLH, we investigated 81 stomach biopsy specimens [Wotherspoon grade (WG) 1, 11 cases; WG 2, 9 cases; WG 3, 20 cases; WG 4, 31 cases; and WG 5, 10 cases]. According to a previously reported algorithm involving PCR for immunoglobulin heavy (IgH) chain locus rearrangement, all 81 cases were divided into three groups: CG/RLH (55 cases), MALT lymphoma (19 cases) groups, and IgH undetectable group (7 cases). We analyzed the CG/RLH and MALT lymphoma groups. The median percentage of IRTA1-positive cells was 0% (range 0%-90.6%) in the CG/RLH group and 43.5% (range 0%-97.6%) in the MALT lymphoma group (p < 0.0001). The median percentage of MNDA-positive cells was 32.4% (range 0%-97.6%) in the CG/RLH group and 55.1% (range 0%-97.6%) in the MALT lymphoma group (p = 0.0044). These results indicate that immunohistochemistry for IRTA1 and MNDA can help differentiate gastric MALT lymphoma from CG/RLH.

BACKGROUND: We describe the outcome of ultra-low-dose radiotherapy plus intravitreal methotrexate and rituximab injections for a patient with primary choroidal lymphoma who presented with nodular conjunctival salmon patches and extensive serous retinal detachment.
METHODS: A 34-year-old Iranian man presented with a nodular patch of bulbar conjunctiva in the right eye, and 1+ vitritis. A nearly complete shallow serous retinal detachment, retinal folds, and multifocal yellow choroidal infiltrates were seen during a fundus examination of the right eye. Enhanced depth imaging optical coherence tomography revealed macular retinal folds and an uneven, undulating, \"seasick\" appearance of the choroidal surface with choriocapillaris compression, intraretinal and subretinal fluid, and clusters of optically dense material at the outer retinal level. An incisional biopsy of the conjunctival lesion confirmed the diagnosis of primary choroidal lymphoma with epibulbar involvement. The patient was treated with ultra-low-dose \"boom-boom\" radiation (4 Gy delivered in two fractions over two consecutive days) as well as intravitreal methotrexate and rituximab injections. After a year, the lesions had completely disappeared, with no adverse effects or recurrence.
CONCLUSIONS: Ultra-low-dose (boom-boom) radiotherapy combined with intravitreal chemotherapy and/or immunotherapy may be an effective treatment for primary choroidal lymphoma with anterior epibulbar extension and diffuse subretinal fluid with favorable response and minimal side effects.