Hepatic angiomyolipoma resembling an inflammatory pseudotumor of the liver. A case report

Hepatic angiomyolipoma (AML) may demonstrate a marked histologic diversity and is frequently misdiagnosed. HMB45 is a promising marker for this tumor and is expected to facilitate the recognition of some AMLs with unusual morphology. We report on a case of hepatic AML exhibiting histologic features that were similar to inflammatory pseudotumor (IPT) or to IPT-like follicular dendritic cell (FDC) tumor of the liver. The patient was a 21-year-old Japanese woman with a mass in the left lobe of the liver (70 x 73 mm). There were no clinical features of tuberous sclerosis. Histologically, numerous inflammatory cells, including small lymphocytes, plasma cells, and histiocytes, showed diffuse infiltration throughout the lesion. However, the present case also shared some of the morphologic findings of hepatic AML, including clusters of smooth muscle cells with clear cytoplasm, a few scattered adipose cells, and thick-walled blood vessels. Moreover, the smooth muscle cells consisted of spindle-shaped cells or larger, more rounded cells with either clear cytoplasm or eosinophilic epithelioid cell features positive for vimentin, muscle-specific actin, and smooth muscle actin. HMB45 immunostaining confirmed the diagnosis of AML. The present case indicates that IPT or IPT-like FDC tumor should be added to the list of differential diagnoses for AML of the liver.

Inflammatory myofibroblastic tumor of the larynx in a 2-year-old male

Inflammatory myofibroblastic tumor (IMT) is an uncommon neoplasm that is usually located in the lung in the pediatric population. These tumors contain a variety of cell types with the myofibroblast being dominant. When located in the upper airway, IMTs tend to be less aggressive, but have the potential for local invasion and recurrence. We present an unusual case of IMT in the pediatric larynx and review the medical literature describing the common locations, diagnosis, etiology, histology, and treatment of this tumor. The mainstay of treatment is complete surgical excision. Careful and frequent follow-up including frequent fiberoptic laryngoscopy and CT scans are recommended to evaluate for recurrence. More aggressive resection may be necessary if multiple recurrences occur.

Inflammatory pseudotumour (plasma cell granuloma) arising in the maxillary sinus

CONCLUSIONS

Inflammatory pseudotumours in the maxillary sinus may present as malignant tumours and manifest locally aggressive features characteristic of such tumours. Despite their locally destructive features, they pursue a benign course after local excision.

OBJECTIVE

Inflammatory pseudotumour (plasma cell granuloma) is an uncommon non-neoplastic lesion comprising a proliferation of spindle myofibroblasts and chronic inflammatory cells. Despite its benign histopathological nature, it may exhibit aggressive behaviour that is yet to be characterized in the head and neck area.

MATERIAL AND METHODS

We present the cases of two adult patients with inflammatory pseudotumour arising from the maxillary sinus. Immunohistochemistry and polymerase chain reaction for immunoglobulin from tissue sections were performed to confirm the polyclonality of the infiltrating plasma cells.

RESULTS

CT and MRI disclosed expansive soft masses eroding surrounding soft and bony tissues. Histopathologically, the lesions were unencapsulated and composed of numerous plasma cells, histiocytes and spindle cells with minimal nuclear pleomorphism.

Inflammatory pseudotumor of the spleen

Mass-like lesions with histologic features of nonspecific inflammation and mesenchymal repair have been designated as inflammatory pseudotumors. Such lesions occasionally have been observed in a variety of tissues, such as the orbit, spinal meninges, digestive system, heart, soft tissues, mesothelial membranes, and respiratory tract. Splenic involvement is extremely rare. To our knowledge, since Cotelingam and Jaffe first reported 2 cases of splenic inflammatory pseudotumor in 1984, only 74 cases had been reported in the literature till now. We report a 44-year-old female with inflammatory pseudotumor of the spleen. The tumor was found in a routine health evaluation by abdominal ultrasonography. However, further image study of abdominal CT could not rule out a malignant lesion. Hand-assisted laparoscopic splenectomy was performed. Pathological report of the mass revealed an inflammatory pseudotumor.

Cutaneous inflammatory pseudotumor - a spectrum of various diseases?

BACKGROUND

Inflammatory pseudotumor (IPT) also known as inflammatory myofibroblastic tumor (IMT) or plasma cell granuloma (PCG) has been rarely reported in the skin.

METHODS

We describe five patients with cutaneous IPT and present clinicopathologic features along with detailed immunohistochemical analysis including anaplastic lymphoma kinase (ALK)-1.

RESULTS

The patients age ranged from 15 to 89 years with a median of 56 years. All patients presented with solitary, firm, papules and nodules. There was no evidence of constitutional symptoms, local recurrence, or lymph node involvement. Histopathological examination revealed two distinct patterns; one type (n = 3) displayed dense, lymphoplasmacytoid infiltrates containing lymphoplasmacytoid cells and plasma cells with occasional germinal centers and hyalinized collagen bundles but was devoid of a myofibroblastic component. It showed features of tumors previously described as cutaneous PCG. Although an infectious etiology, including Borrelia burgdorferi-specific DNA, could not be demonstrated, we observed many features that overlapped with those of fibrous nodules of acrodermatitis chronica atrophicans. The other pattern (n = 2) revealed spindled myofibroblasts focally arranged in a fascicular pattern, an admixed lymphoplasmacytoid infiltrate set in a background of thickened collagen bundles, findings akin to the conventional type of IMT. The cases with a myofibroblastic component (n = 2) did not show any evidence of ALK-1 reactivity.

CONCLUSIONS

We believe that the term cutaneous IPT subsumes lesions of diverse etiology. Tumors with detectable myofibroblasts represent true cases of IMT. Cutaneous PCG is a discrete disorder biologically distinct from conventional IMT representing a reaction pattern that is also found in disorders, such as spirochete-induced fibroid nodules and localized chronic fibrosing vasculitis.

Immunohistochemical localization of metallothionein in chronic pancreatitis

Metallothionein (MT) is a low-molecular weight intracellular protein, rich in sulfhydryl residues, and able to bind bivalent metals. MT, like Zn, is a component of the diversified elements of antioxidant system. Recent studies have shown that reactive oxygen species play a role in the pathogenesis and development of chronic pancreatitis. The aim of the study was to identify immunohistochemically (LSAB2-HRP; DAKOCytomation) the localization of metallothionein and to determine MT expression in 9 patients with chronic pancreatitis. Our studies confirm that MT is present in exocrine and endocrine cells of patients with chronic pancreatitis and chronic pancreatitis with concomitant diabetes. They also indicate increased expression of MT, particularly in acinar cells of the pancreas. This suggests that MT is greatly involved in homeostasis of the pancreas and synthesis of pancreatic hormones.

Inflammatory pseudotumor of the parotid gland: report of a case with fine needle aspiration cytology

BACKGROUND

Inflammatory pseudotumor is a rare lesion of the parotid gland. It usually presents as a mass lesion; thus, the clinical and radiologicfeatures often suggest malignancy. To the best of our knowledge, fine needle aspiration cytologic findings in parotid inflammatory pseudotumor have not been reported previously.

CASE

A 59-year-old male presented with a palpable right parotid mass. Computed tomography revealed a mass measuring 2.5 cm in diameter. Fine needle aspiration cytology showed inflammatory cells, foamy histiocytes and groups of spindle-shaped cells without cytologic atypia. A diagnosis of inflammatory pseudotumor was suggested and was confirmed on histology.

CONCLUSION

In the presence of a clinically evident mass in the parotid gland and fine needle aspiration cytologic features of inflammatory cells with sheets of spindle cells, the diagnosis of inflammatory pseudotumor should be suspected. The differential diagnosis of this unusual parotid gland lesion principally includes sialadenitis and myoepithelioma.

A clinicopathological study of inflammatory pseudotumors of the liver with special reference to vessels

BACKGROUND/AIMS

Inflammatory pseudotumor of the liver is rare, and patients with inflammatory pseudotumor frequently undergo unnecessary surgical resection as a result of misdiagnosis of malignancy. In this study, we therefore investigated inflammatory pseudotumor clinicopathologically to clarify its characteristics.

METHODOLOGY

Twenty patients including 3 with inflammatory pseudotumor and 17 with various malignant liver tumors were studied. We further investigated tumor vessels by means of immunohistochemistry using monoclonal antibodies against CD34, factor VIII-related antigen and alpha-smooth muscle actin.

RESULTS

Although serum levels of alkaline phosphatase were significantly higher in inflammatory pseudotumor patients than in other patients, the laboratory data alone could not precisely distinguish inflammatory pseudotumor from other hepatic tumors. On imaging studies such as ultrasonography and computed tomography, significant changes in tumor size, especially size reduction, during relatively short follow-up periods were often observed in inflammatory pseudotumor but not in other liver tumors. An enhancement of the peripheral regions of inflammatory pseudotumor was frequently observed in the early phase of contrast-medium dynamic computed tomography. This might be due to abnormal vessels located in the peripheral regions of inflammatory pseudotumor which might result from obliteration of some pre-existing vessels in portal tracts within inflammatory pseudotumor. Immunohistochemical analysis further revealed that abnormal vessels in the peripheral regions of inflammatory pseudotumor were positively stained with CD34, factor VIII-related antigen and alpha-smooth muscle actin as were tumor sinusoids within hepatocellular carcinoma and tumor capillaries in other malignant liver tumors.

CONCLUSIONS

Although inflammatory pseudotumor seems to have some features in imaging studies, a biopsy is needed for a correct diagnosis of inflammatory pseudotumor.

Plasma Cell Granuloma of the Thyroid and Hashimoto Thyroiditis

Plasma cell granuloma of the thyroid is a rare tumor-like lesion formed by a localized proliferation of inflammatory cells, supported by a stroma of fibrous tissue. Few cases have been previously reported in the medical literature. We report a new case of a 41-year-old man presenting a goiter with primary hypothyroidism (thyroid-stimulating hormone, 70 mIU/L; free thyroxine, < 0.01 pmol/L; triiodothyronine, 0.66 nmol/L) and elevation of thyroid antibodies. Several fine-needle aspiration biopsies of the thyroid were fruitless and total thyroidectomy was performed. Histologic and immunohistochemical study demonstrated the polyclonal nature of the cells and yielded a diagnosis of plasma cell granuloma. Histologic findings of Hashimoto thyroiditis were present too.

p53 Mutation and MDM2 amplification in inflammatory myofibroblastic tumours

AIMS

The pathogenic mechanism and predictive indicators of biological behaviour of inflammatory myofibroblastic tumour are poorly understood. We investigated molecular abnormalities of p53 and MDM2 in order to assess whether these play an important role in pathogenesis, and whether they also contribute to clinicopathological aggressive phenotype in inflammatory myofibroblastic tumour.

METHODS AND RESULTS

We compared the immunohistochemical expression of calponin, h-caldesmon, ALK, and p53 gene mutation and MDM2 gene amplification with clinicopathological findings in 15 cases of inflammatory myofibroblastic tumour. Histologically, cellular atypia was observed in five (33.3%) out of 15 cases. Local recurrences were observed in two (14.3%) of 14 informative cases, but no distant metastasis was observed. The expression of calponin (9/14; 64%) but not h-caldesmon (0/14; 0%) was seen, which suggested myofibroblastic differentiation. ALK expression was seen in eight (53.3%) out of 15 cases, particularly in patients under 40 years old. Nuclear expression of p53 protein was recognized in only one (6.7%) of 15 cases, and polymerase chain reaction single-strand conformation polymorphism followed by direct sequencing revealed p53 gene missense mutations in two (13.3%) of 15 cases. Nuclear expression of MDM2 was seen in four (26.7%) of 15 cases, and the MDM2 gene amplification was observed in two of the four cases.

CONCLUSION

Inflammatory myofibroblastic tumour shows a wide spectrum of cellular atypia and biological behaviour with p53 and MDM2 expression. However, the alterations in the p53 pathway seem not to play a major role in the pathogenesis of inflammatory myofibroblastic tumour.

Inflammatory myofibroblastic tumors of the kidney: a clinicopathologic and immunohistochemical study of 12 cases

Inflammatory myofibroblastic tumor is a rare entity composed of spindle cells admixed with variable amounts of extracellular collagen, lymphocytes, and plasma cells. In the genitourinary tract, inflammatory myofibroblastic tumor most commonly occurs in the bladder. Isolated case studies of inflammatory myofibroblastic tumor of the kidney, renal pelvis, and ureter have been previously reported. Our series includes 12 cases of inflammatory myofibroblastic tumor occurring in the renal pelvis (six cases), renal parenchyma (four cases), and immediate perirenal soft tissue (two cases). Clinical presentation included flank pain (two patients), painless gross hematuria (one patient), and ureteropelvic junction stenosis with hydronephrosis (one patient). The remaining eight patients were asymptomatic. All patients underwent nephrectomy. The tumors were characterized by firm white tissue or had a myxoid "gelatinous" appearance. Three histologic patterns were identified in the tumors, including a myxoid vascular pattern, a compact spindle cell pattern, and a hypocellular fibrous pattern. Immunohistochemical and electron microscopic studies supported a myofibroblastic proliferation. All cases were negative for anaplastic lymphoma kinase. Follow-up was available in eight cases and ranged from 1 to 17 years with no evidence of recurrence. Based on this series, renal inflammatory myofibroblastic tumor is a proliferative lesion of myofibroblasts of uncertain pathogenesis with no identified potential for recurrence or metastases.

[Calcified pseudotumor of the pleura: description of a case]

We describe a calcifying fibrous pseudotumour of pleura in a 46-year-old female, smoker. The patient presented with a well-delimited pleural mass, 3-cm across, located at the base of the right lung and attached to the lung with a short pedicle. Seven years after surgical excision of the mass, the patient is alive and well. Microscopically, the lesion was mostly composed of dense collagenous tissue, with sparse benign spindle cells, a rich inflammatory infiltrate and scattered calcifications, sometimes laminated. Immunohistochemically, spindle cells were positive for vimentin and negative for smooth muscle actin, desmin, S100 protein, CD34, CD99 and Bcl2. Calcifying fibrous pseudotumour is rare in the pleura. Pertinent data from the literature and problems in differential diagnosis are briefly discussed.

Calcifying fibrous 'pseudotumor': clinicopathologic study of 15 cases and analysis of its relationship to inflammatory myofibroblastic tumor

Calcifying fibrous pseudotumor (CFP) has been postulated to be a "late" stage of inflammatory myofibroblastic tumor (IMT). We analyzed 15 cases (8 females and 7 males; aged 1 to 65 years). The anatomic distribution was wide, including 3 cases each in neck, mesentery/omentum, and GI tract and 2 cases each in mediastinum and paratesticular sites. Follow-up information was available in 10 patients (range 4 to 228 months). Local recurrence occurred in 3 patients and was repeated in 2. Tumor size ranged from 0.6 to 25 cm. Lesions were well-circumscribed hypocellular spindle cell proliferations with dense stromal collagen, a lymphoplasmacytic infiltrate, and stromal calcifications. Features of conventional IMT were not seen. Immunostaining showed CD34 positivity in most cases as well as rare cells positive for smooth muscle actin and desmin, and consistent negativity for ALK-1 and S-100 protein. These findings suggest that CFP is a distinctive benign mesenchymal neoplasm with a low risk for recurrence and, therefore, best labelled as "calcifying fibrous tumor." There is no convincing evidence to support an association between CFP and IMT.

Intravascular inflammatory myofibroblastic tumors in infancy

Inflammatory myofibroblastic tumor (IMT), previously described as inflammatory pseudotumor, can occur at any age but is a recognized soft tissue tumor of childhood. Less than 10 previous cases have been described of IMT affecting the heart, in patients ranging from 5 months to 17 years of age. We present three unusual, but similar, cases of IMT in infants, which were all predominantly intravascular in location, one of which was associated with death due to angiodestructive lesions of the coronary and cerebral arteries. These cases demonstrate an apparently distinct phenotype, with a predominant intravascular location of the tumor. Furthermore, this series highlights the difficulty in categorizing such lesions as benign versus malignant on histological grounds alone. IMT should be considered in the differential diagnosis of unusual pediatric intravascular spindle cell lesions.

Plasma cell granuloma of the thyroid

Plasma cell granuloma of the thyroid is an uncommon lesion; only 6 cases have been reported in the English literature to date. All reported cases occurred in women, mostly after the age of 50 years. We report a case of plasma cell granuloma of the thyroid in a 46-year-old woman with a 20-year history of euthyroid goiter and a positive family history of goiter in 3 close relatives. The lesion was composed of sheets of plasma cells involving the entire parenchyma that histologically resembled plasmacytoma. Plasmacytoma was excluded by demonstration of polyclonal kappa/lambda light chain immunostaining and by lack of evidence of clonal bands by polymerase chain reaction for immunoglobulin heavy-chain gene rearrangement. Similarly, the predominant histologic pattern in all previously reported cases is that of marked plasma cell infiltration. A family history of thyroid disease (goiter, thyroiditis) was associated with diffuse involvement of the thyroid. Prognosis after surgery is excellent, and to our knowledge no cases of malignant transformation or recurrence have been described.

Inflammatory myofibroblastic tumors (inflammatory pseudotumors) of the gastrointestinal tract: how closely are they related to inflammatory fibroid polyps?

Inflammatory myofibroblastic tumors (inflammatory pseudotumors) and inflammatory fibroid polyps of the gastrointestinal tract both feature prominent inflammatory infiltrates admixed with spindle-shaped fibroblasts/myofibroblasts set in a collagenous, fibrovascular, or myxoid stroma. Erroneously, some have considered inflammatory fibroid polyps to be intraluminal manifestations of inflammatory myofibroblastic tumors. In this study, we have characterized the histopathology of inflammatory myofibroblastic tumors, tumors that have only rarely been reported in the gastrointestinal tract, and have focused on whether inflammatory myofibroblastic tumors and inflammatory fibroid polyps in the gastrointestinal tract are distinct or similar. Clinical, histopathologic, and immunohistochemical features of 38 inflammatory myofibroblastic tumors limited to the wall of the gastrointestinal tract were compared with those of 45 inflammatory fibroid polyps. Compared to patients with inflammatory fibroid polyps, those with inflammatory myofibroblastic tumors were younger (mean age 41 years vs. 53 years); had larger tumors (mean 8 +/- 5.2 cm vs. 3.6 +/- 4.6 cm); presented with abdominal pain, fever, and weight loss more frequently and less frequently had bowel obstruction. Inflammatory fibroid polyps had more eosinophils and fibrosis and fewer lymphoid cell infiltrates than inflammatory myofibroblastic tumors. A regular vascular pattern was a feature of inflammatory fibroid polyps but not of inflammatory myofibroblastic tumors. Most (82%) inflammatory fibroid polyps were positive for CD34 versus none of the inflammatory myofibroblastic tumors. Smooth muscle actin was more frequently positive in inflammatory myofibroblastic tumors than in inflammatory fibroid polyps (86% versus 13%). Inflammatory myofibroblastic tumors were much less frequent and were more evenly distributed in the gastrointestinal tract than inflammatory fibroid polyps. Both appear to be benign processes. Inflammatory myofibroblastic tumors, but not inflammatory fibroid polyps, had a tendency to recur. In conclusion, inflammatory myofibroblastic tumors of the gastrointestinal tract are extremely rare and differ clinically, histologically, and immunohistochemically from inflammatory fibroid polyps.

Fibroma and inflammatory myofibroblastic tumor of the heart

Cardiac fibroma and inflammatory myofibroblastic tumor (IMT) of the heart are rare lesions occurring in young patients and having pathologic similarities. We compared the morphologic and immunohistochemical features of seven cardiac fibromas, including one biopsied at birth and removed 4 years later, and two IMTs of the heart diagnosed at Marie Lannelongue Surgical Center (Le Plessis Robinson, France) between 1980 and 1999. Cardiac fibromas occurred in five females and two males and were surgically biopsied (n = 2) or removed (n = 6) between the ages of 8 days to 31 years (mean 7 +/- 12 years). Inflammatory myofibroblastic tumors were removed in two male patients, aged 13 weeks and 1 year, both alive and well 9 months and 5 years after surgery, respectively. Fibromas were ventricular lesions measuring 3 to 10 cm (mean, 5.7 +/- 2.2 cm). They contained entrapped myocytes and wavy elastic fibers. Three cases contained calcifications. Spindle cells were monomorphic. Their nucleus had a thin chromatin without nucleolus. Mitoses and extramedullary hematopoiesis were only observed in fibromas from patients younger than 5 months (n = 5) while prominent collagen fibrosis was present in fibromas from patients older than 4 years (n = 3). Inflammatory myofibroblastic tumors were endocardial lesions measuring 2 and 2.5 cm. They were covered by fibrin. Spindle cells were larger than in fibromas. Their nucleus had obvious nucleoli. They were associated with numerous inflammatory cells in a variable amount of myxoid background. Occasional mitoses and foci of necrosis were present. Spindle cells in both fibromas and IMTs strongly expressed smooth-muscle actin and were negative for desmin, CD34, S-100 protein, and p53. Our study shows that IMT must be considered in the differential diagnosis of cardiac fibroma especially in cases of inflammatory syndrome, location outside the ventricular myocardium, or multinodular lesions. Morphologic analysis permits the correct diagnosis, while immunochemistry shows a myofibroblastic differentiation in both lesions.

Inflammatory pseudotumor and sarcoma of urinary bladder: differential diagnosis and outcome in thirty-eight spindle cell neoplasms

We assessed diagnostic criteria among 38 spindle cell tumors of the urinary bladder and obtained follow-up in 36 patients. Patients comprised 28 males and 10 females aged 2.5 months to 87 years. Hematuria was the commonest presenting symptom (27 patients). After review and immunohistochemical workup, 17 patients had inflammatory pseudotumor (myofibroblastic tumor), 4 postoperative spindle cell nodule, 1 leiomyoma, 13 sarcoma (7 low-grade; 6 high-grade), and 3 carcinoma. Mean age was 38 years for pseudotumor (range 15 to 74), 65 for postoperative spindle cell nodule, 51 for sarcoma, and 76 for carcinoma. Size of pseudotumor averaged 4.4 +/- 0.7 cm (range 1.5 to 13.0), similar to sarcoma, 4.0 +/- 0.6 cm (range 0.5 to 7.0). Similar proportions of benign tumors and sarcomas had muscularis propria invasion. The criteria that best differentiated sarcoma from inflammatory pseudotumor were presence of necrosis at the tumor-detrusor muscle interface in muscle-invasive cases, and nuclear atypia. Sarcoma also had less prominent microvasculature, less variable cellularity, consistently > or =1 mitotic figure per 10 high-power fields, and predominant acute inflammation without plasma cells. p53 protein nuclear immunostaining was moderate, unlike the rare to absent staining in pseudotumors. Because all 12 sarcomas were desmin-negative, we did not call them leiomyosarcoma; they overlapped with benign tumor in epithelial, mesenchymal, and actin immunostaining. Among 12 sarcoma patients, 2 died of tumor (at 3 months). Two of four experienced tumor recurrence after partial cystectomy (2 and 26 months). No pseudotumors recurred after transurethral resection or partial cystectomy, although one patient, 5 months after transurethral resection, had histologically identical pseudotumor that the surgeon considered residual. Another patient with pseudotumor, not a candidate for tumor ablation after transurethral resection, had continued tumor growth and he died of urosepsis. In conclusion, inflammatory pseudotumor, although overlapping with sarcoma in presentation, age range, and size, does not metastasize and remains histologically distinct from low-grade sarcoma.

Calcifying fibrous pseudotumor versus inflammatory myofibroblastic tumor: a histological and immunohistochemical comparison

Calcifying fibrous pseudotumor (CFP), a recently described lesion, is characterized by a predominantly lymphoplasmacytic infiltrate with abundant hyalinized collagen and psammomatous or dystrophic calcifications. The cause and pathogenesis are unclear, but it has been postulated that CFP may represent a sclerosing end stage of inflammatory myofibroblastic tumor (IMT). We compared the histological and immunohistochemical profiles of seven cases diagnosed as CFP and seven as IMT. Histologically, the CFP demonstrated varying degrees of calcifications in addition to fibroblastic proliferation admixed with inflammatory cells composed of lymphocytes, eosinophils, and mast cells. The IMTs rarely contain calcifications and had a myofibroblastic proliferation varying from hyalinized acellular collagen to florid fibroblastic proliferations simulating sarcoma. The inflammatory component was composed primarily of plasma cells and lymphocytes, sometimes arranged as lymphoid aggregates with germinal centers. All CFP cases were diffusely positive for factor XIIIa and negative for smooth muscle actin, muscle-specific actin, and CD34. All IMTs demonstrated diffuse positivity for actin, variable positivity for CD34, and focal positivity for Factor XIIIa. This study demonstrates certain distinct histologic, immunohistochemical, and electron microscopic features between IMTs and CFPs.

Inflammatory pseudotumor of lymph nodes: clinicopathologic and immunohistological study of 11 Japanese cases

We report 11 Japanese cases of inflammatory pseudotumor (IPT) of the lymph node. There were 7 males and 4 females with ages ranging from 5 to 68 years (median; 48). Only 2 patients had systemic lymphadenopathy, and all others had involvement of only 1 lymph node group. Constitutional symptoms such as fever were present in 8 patients and laboratory abnormalities were detected in 5. All patients recovered and were alive and well after 2 to 180 months (median; 32 months). Histologically, the process mainly involved the connective tissue framework of the lymph node, secondarily spreading into the lymph node parenchyma and the perinodal tissue. It was characterized by a storiform growth pattern of myofibroblasts, marked vascularity with associated vascular lesions, and a polymorphous reactive cellular infiltrate in a collagen-rich stroma. An immunohistochemical study revealed numerous myofibroblasts, histiocytes, and vascular endothelial cells expressing vascular endothelial growth factor (VEGF) in 6 cases. It was suggested that VEGF may be involved, in part, in the induction of the angiogenesis of IPT. Moreover, the present study indicates that follicular dendritic cell sarcoma, nasal T/natural killer cell lymphoma, and anaplastic large cell lymphoma should be added to the differential diagnosis from IPT of the lymph node. Int J Surg Pathol 9(3):207-214, 2001

Anaplastic lymphoma kinase expression in inflammatory pseudotumors

Anaplastic lymphoma kinase (ALK), a hallmark of anaplastic large cell lymphoma, has recently been implicated in the genesis of some inflammatory pseudotumors (inflammatory myofibroblastic tumors) in children and young adults. The aim of this study was to determine the frequency of its expression among inflammatory pseudotumors, and to characterize the clinicopathologic features of the positive cases. Sixty-one cases of inflammatory pseudotumors were retrieved from the surgical pathology archives and consultation files. Paraffin sections were immunostained with the antibody ALK1. The patients ranged in age from 0.5 to 79 years (median age, 50 years), with 10 patients (16.4%) younger than 20 years. Five cases (8.2%) were ALK+, including two of six urogenital inflammatory myofibroblastic tumors, none of eight pulmonary inflammatory pseudotumors, three (one adrenal, one small bowel, one liver) of 31 extrapulmonary inflammatory pseudotumors, none of nine hepatic/splenic inflammatory pseudotumors expressing follicular dendritic cell markers and harboring Epstein-Barr virus, and none of seven inflammatory pseudotumors of the lymph node. When only those patients 40 years or younger were considered, the ALK positivity rate became 21.7% (five of 23). All five ALK+ cases occurred in young patients aged 0.5 to 37 years, who were alive and well at 3.5 to 17 years. The tumors exhibited a spectrum of histologic features typical of inflammatory pseudotumors/myofibroblastic tumors, but there was at least focal nuclear atypia. Immunostaining for ALK produced fibrillary or granular cytoplasmic staining in the neoplastic cells, sometimes with cell membrane accentuation. This study confirms that ALK is implicated in a proportion of inflammatory pseudotumors, and is generally associated with a favorable outcome. The results also support the heterogeneity of inflammatory pseudotumors, with the follicular dendritic cell/Epstein-Barr virus-positive cases and those occurring in lymph nodes representing different biologic entities.