Imaging Features of Uncommon Entities That Manifest with Torsion.

Torsion is the twisting of an object along the axis, and various structures (organs and tumors) in the body can twist. Torsion causes initial lymphatic and venous outflow obstruction, leading to congestive edema, enlargement, venous hemorrhagic infarction, and surrounding edema. It can also cause subsequent arterial obstruction depending on the degree of torsion, leading to ischemia, infarction, necrosis, gangrene, and surrounding inflammation. Therefore, in several cases of torsion, immediate surgical intervention is required to improve blood flow and prevent serious complications. Clinical manifestations of torsion are often nonspecific and can affect individuals of varying ages and sex. Imaging plays an important role in the early diagnosis and management of torsion. Multiple imaging modalities, including US, radiography, CT, and MRI, are used to evaluate torsion, and each modality has its specific characteristics. The imaging findings reflect the pathophysiologic mechanism: a twisted pedicle (whirlpool sign), enlargement of the torsed structures, reduced blood flow, internal heterogeneity, and surrounding reactive changes. The whirlpool sign is a definitive characteristic of torsion. In some cases, despite poor internal enhancement, capsular enhancement is observed on contrast-enhanced CT and MR images and is considered to be associated with preserved capsular arterial flow or capsular neovascularization due to inflammation. Radiologists should be familiar with the pathophysiologic mechanisms, clinical characteristics, and imaging characteristics of torsion in various structures in the body. Since other articles about common organ torsions already exist, the authors of this article focus on the uncommon entities that manifest with torsion. ©RSNA, 2024.

Unveiling the mille-feuille sign: a key to diagnosing ovarian carcinosarcoma in addition to ovarian metastasis from colorectal carcinoma on MRI.

PURPOSE: To clarify the diagnostic utility and formation of the Mille-feuille sign for ovarian carcinosarcoma (OCS) on MRI, and to evaluate the other MRI findings and serum markers compared to ovarian metastases from colorectal carcinoma (OMCRC). METHOD: Three blinded radiologists retrospectively reviewed MR images of 12 patients with OCS, 18 with OMCRC, and 40 with primary ovarian carcinoma (POC) identified by the electronic database of radiology reports. The interobserver agreement was analyzed using Fleiss' kappa test. Their MRI characteristics and tumor markers were compared using Fisher's exact test and Mann-Whitney's U test. Receiver operating characteristic curve analyses were used to determine the cutoff points for the ADC value. This study was approved by the institutional ethics committee. RESULTS: Interobserver agreement analysis was moderate or higher for all MRI characteristics. The frequency of Mille-feuille sign was comparable for both OCS and OMCRC groups, and predominantly higher than that of the POC group (p < 0.001, p < 0.001), respectively. Pathologically, the Mille-feuille sign in OCS reflected alternating layers of tumor cells with stroma and necrosis or intraluminal necrotic debris. Compared to OMCRC, intratumoral hemorrhage (p = 0.02), margin irregularity (p = 0.048), unilateral adnexal mass (p = 0.02), and low ADC values (p < 0.01) were more frequently observed and serum CEA levels was significantly lower (p = 0.007) in the OCS group. Under setting of the cutoff value of ADC at 0.871 × 10-3mm2/s, the discriminative ability for OCS showed 66.7% sensitivity, 94.4% specificity, and 81.0% accuracy, respectively. CONCLUSIONS: The Mille-feuille sign was seen in both OCS and OMCRC. MR findings of intratumoral hemorrhage, margin irregularity, unilateral adnexal mass, low ADC values, and low serum CEA levels can be useful in differentiating OCS from OMCRC.

A Case of Solid-Appearing Struma Ovarii: Pitfall in the Assessment Using Ovarian-Adnexal Reporting and Data System Magnetic Resonance Imaging Score.

Struma ovarii is a monodermal teratoma characterized by the presence of >50% thyroid tissue. It is mostly benign; therefore, preoperative diagnosis is important. It usually manifests as a multilocular cystic mass but rarely as a predominantly solid mass. On magnetic resonance imaging (MRI), solid-appearing struma ovarii showed early signal intensity enhancement on dynamic gadolinium-enhanced T1-weighted images, which histopathologically indicates the presence of thyroid tissue with abundant blood vessels. The Ovarian-Adnexal Reporting and Data System (O-RADS) MRI score is a validated classification worldwide for characterizing adnexal lesions. Based on the morphology, signal intensity, and enhancement of any solid tissue on the MRI, the scoring system can be used to classify adnexal lesions into five categories from score one (no adnexal mass) to score five (high risk of malignancy). An adnexal solid mass with a higher signal intensity than that of the myometrium 30-40 seconds after gadolinium (Gd) injection on non-dynamic contrast-enhanced (non-DCE) MRI was assigned a score of 5 (high risk of malignancy).  We present a case of solid-appearing struma ovarii with a higher signal intensity than that of the myometrium 30 seconds after Gd injection on non-DCE MRI, and it was classified as score five preoperatively. Therefore, a total abdominal hysterectomy with bilateral salpingo-oophorectomy was performed despite the presence of a benign ovarian mass. When an adnexal mass with a higher signal intensity than that of the myometrium 30-40 seconds after Gd injection on non-DCE MRI is encountered, struma ovarii should be included in the differential diagnosis, despite the O-RADS MRI score of five and management of the situation should be discussed.

Magnetic resonance imaging features of complete androgen insensitivity syndrome in comparison to Mayer-Rokitansky-Küster-Hauser syndrome.

PURPOSE: Complete androgen insensitivity syndrome (CAIS) and Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) share common clinical features such as female phenotype, vaginal hypoplasia, and primary amenorrhea. Magnetic resonance imaging (MRI) is performed to investigate the cause of primary amenorrhea. However, the MRI features are also similar in both disorders. They are ultimately diagnosed by chromosome testing, but there is a possibility of misdiagnosis if chromosome testing is not performed. This study aimed to identify MRI features that are useful for differentiating CAIS from MRKHS. METHOD: This multicenter retrospective study included 12 patients with CAIS and 19 patients with MRKHS. Three radiologists blindly evaluated the following features: (1) detection of vagina, (2) detection of nodular and cystic structures in the lateral pelvis; undescended testicles and paratesticular cysts in CAIS and rudimentary uteri and ovaries in MRKHS, (3) their location, (4) number of cysts in the cystic structures, and (5) signal intensity on diffusion-weighted images (DWI) and apparent diffusion coefficient (ADC) values of the nodular structures. Statistical comparisons were performed using Mann-Whitney U and Fisher's exact tests. RESULTS: Compared with MRKHS, the CAIS group showed significantly detectable vagina, more ventrally located nodular and cystic structures, fewer cysts within the cystic structures, and nodular structures with higher signal intensity on DWI and lower ADC values. CONCLUSIONS: MRI features of detectable vagina, location of nodular and cystic structures, number of cysts within the cystic structures, signal intensity on DWI and ADC values of the nodular structures were useful in differentiating CAIS from MRKHS.

Prediction of antenatal bleeding and preterm deliveries using placental magnetic resonance imaging in patients with placenta previa.

PURPOSE: This study aimed to clarify associations between subacute hematoma on placental magnetic resonance imaging (MRI), antenatal bleeding, and preterm deliveries in patients with placenta previa (PP) without placenta accreta spectrum (PAS). MATERIALS AND METHODS: This retrospective study investigated 78 consecutive patients with PP (median age, 34.5 years; interquartile range [IQR], 31-37 years) who underwent placental MRI in the third trimester. Patients with PAS detected intraoperatively or pathologically were excluded. Two radiologists evaluated the presence of subacute hematomas and their locations on placental MRI. We examined associations between presence of subacute hematoma and antenatal bleeding, emergency cesarean section (CS), hysterectomy, gestational age (GA) at delivery, birth weight, and amount of blood loss at CS. We also examined the association between perinatal outcome and subacute hematoma location: marginal, retro-placental, or intra-placental. Inter-observer agreement for the detection of subacute hematoma was calculated using kappa analysis. RESULTS: Subacute hematomas were identified on MRI in 39 of the 78 patients (50.0%). Antenatal bleeding and emergency CS were more prevalent in patients with subacute hematoma on MRI (20 patients [51.3%] and 18 patients [46.2%], respectively) than in patients without (7 patients [17.9%], Fisher's exact test, p = 0.004 and 7 patients [17.9%], p = 0.014, respectively). GA at delivery was significantly lower in patients with subacute hematoma (median 36w3d, IQR 35w4d-37w1d) than in patients without (median 37w1d, IQR 36w4d-37w2d; Mann-Whitney test: p = 0.048). Marginal hematoma was significantly associated with antenatal bleeding and emergency CS. Inter-observer agreement for the presence of subacute hematoma was moderate (κ = 0.573). CONCLUSION: Subacute hematoma on placental MRI was associated with antenatal bleeding, emergency CS and shorter GA at delivery in patients with PP. Marginal hematoma was also associated with antenatal bleeding and emergency CS. Placental MRI appears useful for predicting antenatal bleeding and preterm delivery in patients with PP.

Choroid plexus and pituitary gland hemochromatosis induced by transfusional iron overload: Two case reports.

Hemochromatosis is a primary or secondary pathological condition characterized by the deposition of excess iron in the body tissues, which can eventually lead to cellular damage and organ dysfunction. Although excess iron deposition in the central nervous system is rare, involvement of the choroid plexus, pituitary gland, cortical surfaces, and basal ganglia has been reported to date. This case report describes 2 cases of transfusion-induced hemochromatosis involving the choroid plexus and pituitary gland, which were diagnosed by magnetic resonance imaging (MRI). In both cases, gradient echo (GRE) sequences, such as T2 star-weighted image and susceptibility-weighted imaging demonstrated markedly low signal intensity in the choroid plexus. Furthermore, the pituitary gland showed low signal intensity on T2-weighted images in Patient 2. Because these low signal intensities were not seen prior to red blood cell transfusion, they were diagnosed with transfusion-induced hemochromatosis. Brain MRI with GRE sequences was useful in detecting iron deposition in the choroid plexus. Considering that iron deposition in the body tissues can lead to irreversible organ damage, MRI with GRE sequences should be considered for patients with suspected iron overload.

Unfavorable switching of skewed X chromosome inactivation leads to Menkes disease in a female infant.

Menkes disease is an X-linked disorder of copper metabolism caused by mutations in the ATP7A gene, and female carriers are usually asymptomatic. We describe a 7-month-old female patient with severe intellectual disability, epilepsy, and low levels of serum copper and ceruloplasmin. While heterozygous deletion of exons 16 and 17 of the ATP7A gene was detected in the proband, her mother, and her grandmother, only the proband suffered from Menkes disease clinically. Intriguingly, X chromosome inactivation (XCI) analysis demonstrated that the grandmother and the mother showed skewing of XCI toward the allele with the ATP7A deletion and that the proband had extremely skewed XCI toward the normal allele, resulting in exclusive expression of the pathogenic ATP7A mRNA transcripts. Expression bias analysis and recombination mapping of the X chromosome by the combination of whole genome and RNA sequencing demonstrated that meiotic recombination occurred at Xp21-p22 and Xq26-q28. Assuming that a genetic factor on the X chromosome enhanced or suppressed XCI of its allele, the factor must be on either of the two distal regions derived from her grandfather. Although we were unable to fully uncover the molecular mechanism, we concluded that unfavorable switching of skewed XCI caused Menkes disease in the proband.

The first case of hemorrhagic shock and encephalopathy syndrome with fulminant hypercytokinemia associated with pediatric COVID-19.

BACKGROUND: Infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can lead not only to respiratory symptoms but also to neurologic symptoms with various levels of severity. After the worldwide prevalence of Omicron variant, severe neurological manifestations of coronavirus disease 2019 (COVID-19) such as febrile seizure, demyelinating disease, and cerebrovascular disease, have been reported. However, reports of acute encephalopathy in patients with COVID-19 are quite limited. Especially in terms of cytokine storm-inducing hemorrhagic shock and encephalopathy syndrome (HSES), there is no case reported related to COVID-19. CASE PRESENTATION: We describe the case of an 8-year-old girl who presented with fatal HSES associated with pediatric SARS-CoV-2 infection. Status epilepticus occurs after the onset of fever and diarrhea and lasted for at least an hour. Unconsciousness was followed by circulatory failure and ultimately leading to death within 2 days after the fever onset. Analysis of forty-eight cytokines and chemokines measured in three consecutive serum samples revealed that interferon (IFN)-γ, interleukin (IL)-6, IL-10, IL-17A, tumor necrosis factor (TNF)-a, IL-8, Interferon gamma inducible protein (IP)-10, and Monocyte chemoattractant protein (MCP)-1, were increased within an hour after the onset of impaired consciousness. CONCLUSION: Here, we describe a case of fatal fulminant encephalopathy with rapid progression because of HSES associated with COVID-19. High levels of cytokines and chemokines observed in this case may be because of the SARS-CoV-2-associated cytokine storm. This study is the first COVID-19-associated case of HSES.

Pulmonary Vein Stenosis after Catheter Ablation for Atrial Fibrillation: An Early Diagnosis Using Unenhanced Computed Tomography.

Pulmonary vein stenosis (PVS) is a serious complication of catheter ablation (CA) for atrial fibrillation (AF). PVS generally occurs several months after CA and presents with non-specific symptoms and imaging findings. There have been reports of delayed diagnoses due to a misdiagnosis as infection, interstitial pneumonia, or organizing pneumonia. We introduced six cases of PVS after CA, all of which showed narrowing of the unilateral pulmonary vessels with or without lobar volume loss in the left lung on unenhanced computed tomography. We report these findings as important results indicating the possibility of PVS after CA for AF and contributing to the early diagnosis and management of PVS.

Optic pathway involvement in the posterior reversible encephalopathy syndrome: A case report and review of the literature.

Posterior reversible encephalopathy syndrome (PRES) is a clinico-radiological condition characterized by reversible vasogenic edema of the white matter and acute neurological symptoms. PRES typically affects the parieto-occipital regions but rarely affects the optic pathway. Herein, we describe a case of central-variant PRES in a 57-year-old man with abnormal signal intensities in the optic pathway on magnetic resonance imaging (MRI). The patient underwent hemodialysis, initiated diuretics and antihypertensive medications, and the abnormal signal intensities of the brainstem and optic pathway on MRI improved. Although rare, PRES can affect the optic pathway, thus suggesting the possibility of fragility of the optic pathway itself to hyperperfusion.

Magnetic resonance imaging findings of sclerosing microcystic adenocarcinoma: A case report and review of the literature.

Sclerosing microcystic adenocarcinoma (SMA) is a rare malignant tumor of the salivary glands that closely resembles cutaneous microcystic adnexal carcinoma (MAC). It was newly listed in the 5th edition of the WHO classification of head and neck tumors. This report describes the case of a 61-year-old woman who presented with masses on the floor of the mouth. The masses showed low signal intensity on T2-weighted images (T2WI) and with low apparent diffusion coefficient (ADC) values. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) revealed a plateau or persistence after rapid initial enhancement. Histopathologically, the tumors comprised small infiltrating strands of cells that formed small ducts and cysts embedded in thick fibrous stroma, consistent with SMA. Low signal intensity on T2WI with a low ADC value and a plateau or persistence after rapid initial enhancement on DCE-MRI reflect the fibrous and cellular components of the tumor and can be considered characteristic MRI findings of SMA.

Intradural Chordoma Mimicking an Epidermoid Cyst on Imaging.

Chordomas are rare, locally aggressive, primary bone tumors derived from primitive notochord remnants. They almost always arise within the axial skeleton, particularly in the skull base and the sacrococcygeal region. They usually present as extradural tumors, but rarely, they present as entirely intradural tumors. This report describes a case of intradural chordoma that mimicked an epidermoid cyst. A 72-year-old woman was incidentally found to have a prepontine extra-axial mass on magnetic resonance imaging. The mass gradually increased in size, and she felt discomfort in the right cheek area. The mass showed similar signal intensity to cerebrospinal fluid on T1-weighted images and T2-weighted images, but high signal intensity on fluid-attenuated inversion recovery images and diffusion-weighted images. Because the presence of very faint contrast enhancement was not noticed, the mass was preoperatively diagnosed as an epidermoid cyst. Tumor resection was performed, and the histopathological diagnosis was chondroid chordoma. Since intradural chordoma may resemble an epidermoid cyst on imaging, radiologists should check carefully for the presence of contrast enhancement and suggest the possibility of intradural chordoma.

Massive true thymic hyperplasia with osseous metaplasia.

True thymic hyperplasia is defined as an increase in both the size and weight of the gland, while maintaining a normal microscopic architecture. Massive true thymic hyperplasia is a rare type of hyperplasia that compresses adjacent structures and causes various symptoms. Limited reports address the imaging findings of massive true thymic hyperplasia. Herein, we report a case of massive true thymic hyperplasia in a 3-year-old girl with no remarkable medical history. Contrast-enhanced CT revealed an anterior mediastinal mass with a bilobed configuration containing punctate and linear calcifications in curvilinear septa, which corresponded to lamellar bone deposits in the interlobular septa. To our knowledge, this is the first report of massive true thymic hyperplasia with osseous metaplasia. We also discuss the imaging features and etiology of massive true thymic hyperplasia with osseous metaplasia.

Development of an Algorithm to Differentiate Uterine Sarcoma from Fibroids Using MRI and LDH Levels.

BACKGROUND: This study aimed to establish an evaluation method for detecting uterine sarcoma with 100% sensitivity using MRI and serum LDH levels. METHODS: One evaluator reviewed the MRI images and LDH values of a total of 1801 cases, including 36 cases of uterine sarcoma and 1765 cases of uterine fibroids. The reproducibility of the algorithm was also examined by four evaluators with different imaging experience and abilities, using a test set of 61 cases, including 14 cases of uterine sarcoma. RESULTS: From the MRI images and LDH values of 1801 cases of uterine sarcoma and uterine fibroids, we found that all sarcomas were included in the group with a high T2WI and either a high T1WI, an unclear margin, or high LDH values. In addition, when cases with DWI were examined, all sarcomas had high DWI. Among the 36 sarcoma cases, the group with positive findings for T2WI, T1WI, margins, and serum LDH levels all had a poor prognosis (p = 0.015). The reproducibility of the algorithm was examined by four evaluators and the sensitivity of sarcoma detection ranged from 71% to 93%. CONCLUSION: We established an algorithm to distinguish uterine sarcoma if tumors in the myometrium with low T2WI and DWI are present.

A case of germinoma located in the fornix inducing transsynaptic atrophy of the Papez circuit.

Germinoma is a rare CNS germ cell tumor preferentially affecting children and young adults. Intracranial germinomas arise typically in the neurohypophysis and pineal region and occasionally in the basal ganglia and thalamus. Germinomas in the basal ganglia and thalamus are characterized by the ipsilateral cerebral and brainstem hemiatrophy with slowly progressive neurological deficits, which is due to tumor infiltration into the thalamocortical and corticospinal tract and induction of anterograde and retrograde Wallerian degeneration. We report an 11-year-old boy with a mass located in the fornix incidentally discovered on the first work-up of his minor head injury. Imaging findings revealed the ipsilateral atrophy of the mammillary body and the fornix. Stereotactic brain biopsy was performed and the final diagnosis was germinoma. The ipsilateral atrophy of the mammillary body and the fornix implied the transsynaptic degeneration via the Papez circuit. We discuss the unique nature of germinomas and underlying pathological mechanisms.

Magnetic Resonance Imaging Findings of Lymphoepithelial Carcinoma of the Submandibular Gland: A Case Report.

Lymphoepithelial carcinoma (LEC) is an uncommon neoplasm strongly associated with Epstein-Barr virus (EBV). LEC of the salivary glands (LECSG) is very rare: the most commonly affected site is the parotid gland, followed by the submandibular gland. This report describes the case of a 58-year-old man who presented with a left submandibular mass that had gradually increased in size over five years. On magnetic resonance imaging (MRI), the mass showed low apparent diffusion coefficient (ADC) values, rapid initial enhancement before reaching a plateau on dynamic contrast-enhanced MRI (DCE-MRI), and internal septal-like enhancement. Histopathologically, the tumor comprised polygonal or round tumor cells with atypical or pleomorphic nuclei and numerous lymphocytes, separated by heavy fibrosis. Immunohistological findings were positive for AE/AE3, CD20, and EBV-encoded small RNA in situ hybridization (EBER-ISH), consistent with LEC. A low ADC value with rapid initial enhancement before reaching a plateau on DCE-MRI was thought to reflect abundant cellular components with tumor neoangiogenesis, whereas internal septal-like enhancement reflects separating heavy fibrosis. To the best of our knowledge, this is the first case report describing ADC value and DCE-MRI findings of LECSG, and these findings can be considered characteristic MRI findings of LECSG.

Imaging of extrapontine myelinolysis preceding central pontine myelinolysis in a case of ornithine transcarbamylase deficiency with hyperammonaemia and hypokalaemia.

Background: Patients with ornithine transcarbamylase deficiency (OTCD) often present with severe hyperammonaemia. We report a case of osmotic demyelination syndrome (ODS) secondary to the treatment of hyperammonaemia due to OTCD, a disease requiring early diagnosis, as it can have a severe prognosis. Case: A girl toddler was brought to the hospital with a complaint of somnolence, presenting with hyperammonaemia and liver failure, and was diagnosed with OTCD. Treatment was started immediately, and the ammonia level returned to the normal range within 24 hours. On days 13-20, another treatment was commenced for re-elevated ammonia levels, which subsequently returned to within the reference range; however, mildly impaired consciousness persisted. Hypokalaemia coincided with temporary intravenous treatment and continuous haemodialysis. T2-weighted magnetic resonance images revealed lesions as high-signal areas in the bilateral putamen on day 11 (extrapontine myelinolysis (EPM)) and in the pons on day 51 (central pontine myelinolysis (CPM)). Consequently, ODS was diagnosed. Conclusion: When interpreting magnetic resonance images of patients under acute treatment for hyperammonaemia due to OTCD, a condition that may be complicated by hypokalaemia, paying attention to findings suggesting EPM may help detect ODS before CPM appears and may improve patient prognosis.

A Case of Ruptured Decidualized Ovarian Endometrioma: Usefulness of Serial MRI for Determining Adequate Management.

Decidualization can originate in ovarian endometrioma by elevated serum progesterone levels during pregnancy, which mimics malignancy on ultrasonography. Moreover, decidualized ovarian endometrioma may rupture and cause acute abdominal pain during pregnancy. Magnetic resonance imaging (MRI) is reportedly useful in differentiating decidualized ovarian endometriomas from malignancies. However, to our knowledge, serial MRI of decidualized ovarian endometrioma before and after rupture has not been reported. Herein, we report the case of a 39-year-old woman with a ruptured decidualized ovarian endometrioma in which serial MRI was useful for adequate management. She had a history of right ovarian endometrioma. Transvaginal ultrasonography at 20 weeks of gestation showed the known right ovarian endometrioma with mural nodules that were not evident before pregnancy. MRI for further evaluation showed ovarian endometrioma with mural nodules with signals similar to those of the placenta. Based on the MRI findings, we diagnosed a decidualized ovarian endometrioma. At 27 weeks of gestation, she complained of sudden abdominal pain, for which MRI was performed. MRI showed disappearance of the ovarian endometrioma and bloody ascites, based on which we diagnosed a ruptured ovarian endometrioma. The abdominal pain subsided immediately, and a conservative observational treatment approach was taken. At 37 weeks of gestation, right ovarian cystectomy was performed simultaneously with an elective cesarean section, which revealed a ruptured decidualized ovarian endometrioma. Our findings demonstrate that the accurate diagnosis of a ruptured decidualized ovarian endometrioma on serial MRI can contribute to its management.

Transient atypical lymphoplasmacytic proliferation of the endometrium associated with pyometra: a case report.

Plasmablastic lymphoma is a mature B-cell neoplasm with plasmablastic differentiation, often associated with human immunodeficiency virus (HIV) infection and other forms of immunosuppression. Although it is usually an aggressive disease, spontaneous regression has been seen in a few cases. Plasmablastic lymphoma of the uterus is rare. We report a case of atypical lymphoplasmacytic proliferation resembling plasmablastic lymphoma associated with pyometra that disappeared completely as the pyometra resolved. A 76-year-old HIV-negative woman presented with abnormal vaginal bleeding. Ultrasound and MRI findings were consistent with pyometra diagnosis. Endometrial biopsy revealed large plasmablastoid cells with abundant cytoplasm and prominent nucleoli proliferating in the endometrium. Immunohistochemistry showed that large cells stained positive for CD138, CD79a, and MUM1, and negative for CD20, PAX5, CD3, and CD5. Ki67 labelled at least 80% of the large cells. Epstein-Barr virus was detected in a small number of cells. The histologic picture was highly indicative of lymphoma, especially plasmablastic lymphoma, though the clinical context was unusual. As the pyometra was treated and resolved, the intrauterine abnormality disappeared completely. The patient has been well after 16 months with no sign of recurrent disease. This case underscores the sometimes blurry distinction between benign inflammation and lymphoma.