Eosinophilic pancreatitis: a rare entity that can mimic a pancreatic neoplasm

Eosinophilic pancreatitis is a rare disorder that is frequently diagnosed only after pancreatic resection for suspected pancreatic tumor. It typically occurs in the setting of either eosinophilic gastroenteritis or the hypereosinophilic syndrome. Isolated eosinophilic infiltration of the pancreas is less common. We describe a case of a 36-year-old man who presented with the clinical symptoms of acute pancreatitis. Radiologic evaluation revealed an obstructive pancreatic lesion suspicious for carcinoma. Pathologic examination of the resection specimen revealed a dense infiltrate of eosinophils in the pancreas. Although an uncommon condition, eosinophilic pancreatitis is a syndrome lacking well-defined causes that can be associated with eosinophilic gastroenteritis, a treatable condition, or the potentially fatal hypereosinophilic syndrome. While the radiographic features of this condition can vary widely, eosinophilic infiltration of the pancreas with or without involvement of the gastrointestinal tract is the pathologic feature common to all of the previously reported cases.     

Localized intrapancreatic malignant mesothelioma: a rare entity that may be confused with other pancreatic neoplasms

Malignant mesothelioma usually presents with diffuse involvement of the pleura or peritoneum. Circumscribed or localized malignant mesothelioma has been described in these locations, as well as the viscera, in which case it may cause diagnostic confusion with other, more common entities. Herein, we describe the first well-documented case of primary intrapancreatic malignant mesothelioma in the English literature. The patient was an otherwise healthy 39-year-old woman who presented with a symptomatic mass in the head of the pancreas that was completely resected via pancreaticoduodenectomy. The tumor was composed of cysts, papillae, and tubules lined by cells with abundant eosinophilic cytoplasm and immunohistochemically expressed CA-125, calretinin, and D2-40. Follow-up revealed no evidence of residual or recurrent disease 32 months after surgery. This report also describes the clinical and pathologic characteristics of an intrapancreatic mesothelioma and provides a review of the literature regarding entities that may be considered in the differential diagnosis of this tumor.     

Non-lymphoid lesions that may mimic cutaneous hematopoietic neoplasms histologically

This review considers neoplastic lesions that originate in the skin, and which have the potential to imitate hematopoietic proliferations at a histological level. They include lymphoepithelioma-like carcinoma, Merkel cell carcinoma, benign lymphadenoma, pseudolymphomatous angiosarcoma, lymphadenoid dermatofibroma, lymphomatoid atypical fibroxanthoma, histiocytoid (epithelioid) hemangioma, and inflamed melanocytic lesions. The clinical and pathological features of those tumors are considered.     

Proliferative lesions of the prostate that mimic carcinoma

Increasing numbers of needle biopsies are being taken to exclude early prostate cancer. Many of these contain appearances that mimic and may be confused with prostate cancer. Postatrophic hyperplasia and basal cell hyperplasia are the most frequent and are variants within nodular hyperplasia. Sclerosing adenosis is a proliferation of both epithelial and stromal spindle cells with myoepithelial features. Atypical adenomatous hyperplasia is a controversial lesion which some consider might be a precursor to adenocarcinoma, although most evidence does not support this. Verumontanum mucosal gland hyperplasia is rare, also being restricted to the verumontanum, utricle, and posterior urethra. Sampling of Cowper's glands only occurs in apical biopsies. In different ways, each of the lesions contains morphological features that can resemble adenocarcinoma, particularly when viewed ‘out of context’ in small biopsy specimens and in the absence of the usual anatomical cues. The ‘gold standard’ of diagnosis remains accurate and detailed morphology performed to a consistently high standard using consensus-agreed criteria. This article describes the lesions and emphasizes those diagnostic features that distinguish them from adenocarcinoma. Recommendations are made with respect to the surgical pathological reporting of difficult appearances to exclude prostatic adenocarcinoma.     

Uterine hemangioma: a rare pathologic entity

Uterine hemangioma is a rare benign tumor usually presenting with menorrhagia or pregnancy-associated complications. Although the current literature identifies fewer than 50 cases, we in our institution identified 5 similar cases among 3700 patients undergoing total hysterectomy from January 2006 to December 2010. Adenomyosis was the most common preoperative diagnosis among our patients. Vaginal examination, uterine curettage specimens, ultrasonography, and hysterography are usually uninformative, and the definitive diagnosis relies on the final histologic examination. The differential diagnosis includes adenomatoid tumor, lymphangioma, and arteriovenous malformation. Uterine hemangiomas are classified into congenital and acquired. The former is believed to be associated with some hereditary diseases, while the latter is associated with both physical changes and hormone alteration, especially high estrogen level. The best treatment for hemangiomas is unclear. However, it is very important to obtain an accurate diagnosis to prevent overtreatment among reproductive-age women. The prognosis is excellent after hysterectomy.     

Extraskeletal osteogenic sarcoma: a rare entity

A 25-year-old female presented with a rapidly increasing painful swelling around right lower thigh and knee for the last 5 months with distant metastasis in the form of lung involvement. X-ray of the part showed only soft tissue swelling without any bony involvement. A diagnosis of extraskeletal osteosarcoma was made which was confirmed by immunohistochemistry.     

Hepatosplenic T-cell lymphoma is a distinct rare entity: diagnosis by fine-needle aspiration cytology

In this brief report, we have described the fine-needle aspiration cytology (FNAC) of a hepatosplenic T-cell lymphoma (HSTCL) in a 60-year-old female patient. The patient complained of fever and heaviness of left upper abdomen. Ultrasound-guided FNAC of the spleen showed immature lymphoid cells, and a diagnosis of primary non-Hodgkin lymphoma of spleen was offered. Subsequently, the patient underwent splenectomy and wedge biopsy of liver that confirmed the cytological diagnosis. The lymphoma cells were positive for CD3 immunostain. Primary hepatosplenic T-cell lymphoma is a rare entity and may often pose diagnostic problems on FNAC.     

Benign pulmonary lesions that may be misdiagnosed as malignant

Five benign pulmonary lesions that may be misdiagnosed as malignant tumors are reviewed. In three lesions, diagnostic problems arise when a spindle cell component is dominant and obscures other characteristic histologic features. In the inflammatory pseudotumor, correct diagnosis relies on recognition of the benign cytology of the spindle cells and identifying a typical admixture of plasma cell-rich inflammatory cells. For spindle cell carcinoids, useful diagnostic features are the organoid pattern, benign cytology, and neuroendocrine differentiation features of the spindle cells. Localized pleural mesothelioma (fibroma) is composed of benign spindle cells in a fibrocollagenous background; mesothelial differentiation is not present by ultrastructural or immunocytochemical analysis. In sclerosing hemangioma, a complex histology may suggest a number of malignancies. Observation of solid and papillary areas of benign tumor cells, as well as sclerosis of vessel walls and intervening areas, will allow correct diagnosis. Pseudolymphoma, a nodular benign lymphoid infiltrate, is distinguished by its polymorphous and polyclonal composition and numerous germinal centers.     

Nontypeable Haemophilus influenzae strain 2019 produces a biofilm containing N-acetylneuraminic acid that may mimic sialylated O-linked glycans

Previous studies suggested that nontypeable Haemophilus influenzae (NTHI) can form biofilms during human and chinchilla middle ear infections. Microscopic analysis of a 5-day biofilm of NTHI strain 2019 grown in a continuous-flow chamber revealed that the biofilm had a diffuse matrix interlaced with multiple water channels. Our studies showed that biofilm production was significantly decreased when a chemically defined medium lacking N-acetylneuraminic acid (sialic acid) was used. Based on these observations, we examined mutations in seven NTHI strain 2019 genes involved in carbohydrate and lipooligosaccharide biosynthesis. NTHI strain 2019 with mutations in the genes encoding CMP-N-acetylneuraminic acid synthetase (siaB), one of the three NTHI sialyltransferases (siaA), and the undecaprenyl-phosphate alpha-N-acetylglucosaminyltransferase homolog (wecA) produced significantly smaller amounts of biofilm. NTHI strain 2019 with mutations in genes encoding phosphoglucomutase (pgm), UDP-galactose-4-epimerase, and two other NTHI sialyltransferases (lic3A and lsgB) produced biofilms that were equivalent to or larger than the biofilms produced by the parent strain. The biofilm formed by the NTHI strain 2019pgm mutant was studied with Maackia amurensis fluorescein isothiocyanate (FITC)-conjugated and Sambucus nigra tetramethyl rhodamine isocyanate (TRITC)-conjugated lectins. S. nigra TRITC-conjugated lectin bound to this biofilm, while M. amurensis FITC-conjugated lectin did not. S. nigra TRITC-conjugated lectin binding was inhibited by incubation with alpha2,6-neuraminyllactose and by pretreatment of the biofilm with Vibrio cholerae neuraminidase. Matrix-assisted laser desorption ionization-time of flight mass spectometry analysis of lipooligosaccharides isolated from a biofilm, the planktonic phase, and plate-grown organisms showed that the levels of most sialylated glycoforms were two- to fourfold greater when the lipooligosaccharide was derived from planktonic or biofilm organisms. Our data indicate that NTHI strain 2019 produces a biofilm containing alpha2,6-linked sialic acid and that the sialic acid content of the lipooligosaccharides increases concomitant with the transition of organisms to a biofilm form.     

Angiomatoid fibrous histiocytoma: a rare pathologic entity

Angiomatoid fibrous histiocytoma is an unusual tumor, affecting primarily young adults who develop local disease with favorable prognosis. This contrasts with the aggressive natural history of malignant fibrohistiocytoma. We report case of a 9-year-old girl who presented with a tumor mass of soft tissues with an unusual deep location, thereby with non distinctive clinical features. Surgical treatment was performed.     

Metastatic Crohn disease: a rare cutaneous entity

Metastatic Crohn disease is a rare cutaneous disorder characterized by noncaseating, granulomatous skin lesions present at sites anatomically separate from the gastrointestinal tract. It is the least common dermatologic manifestation of Crohn disease, and the differential diagnosis includes numerous similarly appearing, granulomatous skin entities. Males and females appear to be equally affected, and children tend to present with clinical lesions different from those of adults. An integration of clinical information, microscopic findings, and ancillary studies is necessary to accurately diagnose this rare cutaneous disease. Our objective is to review the clinical features, histopathologic characteristics, suggested pathogenesis, differential diagnosis, and current therapeutic options of metastatic Crohn disease.     

Omental anisakiasis: a rare mimic of acute appendicitis

The authors recently encountered a patient with omental anisakiasis who presented with features of acute appendicitis and who made an uneventful recovery following resection of an inflammatory omental mass containing the larva(e). Anisakiasis refers to infestation of humans by species of marine nematode larvae belonging to the subfamily Anisakinae. Although this condition is rarely reported in the United States, it has been well described both in Holland and in the Orient. Several publications in the Japanese literature have detailed the morphology of the parasite and the clinical symptoms of infestation. The source of infestation is most often raw or uncooked fish, the latter widely enjoyed as a foodstuff in the Orient, but less popular in the United States. With the growing popularity of "sushi" bars and the increasing numbers of Americans developing a taste for raw fish, this condition may become more prevalent in the future.     

Cardiac sarcoidosis and sudden death. The heart may look normal or mimic other cardiomyopathies

Cardiac sarcoidosis has been known to give rise to heart failure, arrhythmias and sudden cardiac death. We have a large database of sudden cardiac death cases at the CRY Centre for Cardiac Pathology at Imperial College, London, UK in which we found 17 of 1,720 cases with a diagnosis of cardiac sarcoid. Macroscopic examination showed a variety of findings including left ventricular hypertrophy, a dilated thin-walled left ventricle ,areas of fibrosis, changes resembling arrhythmogenic right ventricular cardiomyopathy and in some cases, no gross abnormalities. Histological examination revealed large areas of fibrosis and focal lymphocytic inflammation mimicking infarction/myocarditis. Careful search had to be made for non-necrotizing granulomata, since the lymphocytic foci, fibrosis and granulation tissue often predominated throughout the heart. The conduction tissue is often not sampled at autopsy despite the history of heart block. The heterogeneous nature of the macroscopic appearance and histological findings means that widespread sampling of the heart and the conduction system is essential in cases of sudden death in order that a diagnosis of myocardial sarcoidosis is not missed.     

Clostridium innocuum is a vancomycin-resistant pathogen that may cause antibiotic-associated diarrhoea

ObjectivesClostridium innocuum can cause extraintestinal infection in patients with underlying diseases. The role of C. innocuum in antibiotic-associated diarrhoea (AAD) remains unknown.MethodsClinical information of 103 patients from whom C. innocuum was isolated was reviewed. We carried out cellular and animal experiments to examine the pathogenic potential of C. innocuum in AAD.ResultsEighty-eight per cent (91/103) of the 103 patients received antibiotics within 2 weeks of diarrhoea onset. Patients were further classified into two groups, severe colitis and diarrhoea, according to clinical severity level. The mortality rate was 13.6% (14/103) among the patients from whom C. innocuum was isolated. The lowest concentrations at which 90% of the isolates were inhibited for metronidazole and vancomycin were 0.5 and 16 mg/L, respectively. All isolates tested were susceptible to metronidazole but resistant to vancomycin. Nineteen randomly selected isolates (ten from severe colitis group, nine from diarrhoea group) were subjected to further in vitro cellular examinations. The level of cytotoxicity to Vero cells was significantly higher in isolates from the severe colitis group at both 24 and 48 hours after inoculation (24 and 48 hours, p 0.042 and 0.033, respectively). We observed apoptotic changes that subsequently led to cell death in C. innocuum–infected Vero cells. Tissue damages, necrotic changes and oedema were observed in the mouse ileal loop infected by C. innocuum.ConclusionsVancomycin-resistant C. innocuum may play a potential role as a causative agent of AAD. The clinical manifestations of AAD caused by C. innocuum were diarrhoea or severe colitis, including pseudomembranous colitis.