Reticular Growth Pattern Research Articles

Clinicopathologic and molecular characteristics of myxoid angiomatoid fibrous histiocytoma

Objective: To investigate the molecular genetic and clinicopathologic characteristics, immunophenotypes, diagnostic and differential diagnostic features of myxoid angiomatoid fibrous histiocytoma (MAFH). Methods: Three cases of MAFH were collected from the archives of Zhejiang Provincial People's Hospital between January 2015 to August 2018. The clinical and radiologic features, histomorphology, immunohistochemistry, molecular genetics and prognosis were analyzed. Results: Patients consisted of 2 women and 1 man aged 37 years, 46 years, and 57 years, respectively. The clinical manifestations of 3 patients were presented as a painless, slowly-enlarged mass with a duration ranging of 2 weeks, 2 months and 50 years. These tumors were located at the deep somatic soft tissue of extremities or limbs (right hip, left forearm, left wrist, respectively) and 2 were preoperatively considered as ganglion cyst or giant cell tumor of tendon sheath by imaging examinations. The diameter of circumscribed mass lesion was ranged from 3.0 to 7.5 cm, which exhibited a gray white to tan and gelatinous cut surface. Extensive hemorrhage and cystic changes were observed in 2 cases. Under low magnification, all tumors showed a dense fibrous pseudo-capsule with a peritumoral lymphoplasmacytic cuff and a multi-nodular growth pattern. Blood-filled cystic spaces were observed in 2 tumors. The myxoid stroma occupied 60.0%, 80.0% and 90.0% area of the entire tumor, respectively. Within the myxoid areas, tumor cells were oval to stellate and arranged in cord-like, microcystic and reticular growth patterns. Transitions of myxoid tumor components to more solid areas with typical histology of angiomatoid fibrous histiocytoma (AFH) were observed at least focally in all the three cases. The tumor cells exhibited minimal atypia and scarce mitoses (1 to 2/50 HPF) without necrosis, and prominently focal intracytoplasmic vacuoles were identified in one case. The results of immunohistochemistry staining showed that, 2/3 cases focally expressed desmin, 2/3 focally expressed epithelial membrane antigen (EMA), and 1/3 focally expressed CD99. The positive index of Ki67 was approximately 1% to 5%. Fluorescence in situ hybridization analysis showed that EWSR1 gene rearrangement occurred in all of the three cases. During the period of follow-up, one case showed local recurrence at 15 months, one case showed postoperative recurrence at 24 months, and the recurrent tumor slowly grew for 120 months until the second resection, without recurrence at the following 2 months. The left case showed a disease-free survival at 32 months. Conclusions: MAFH is a rare subtype of AFH with a low-grade behavior and may lead to diagnostic confusions. Carefully searching for the typical AFH histomorphology and combining with EWSR1 gene rearrangement test can help to distinguish MAFH from other mimickers.

Identification of a specific ultrasonographic finding for differentiating hepatic angiomyolipoma from hepatocellular carcinoma

ObjectiveTo identify specific ultrasonographic features that differentiate hepatic angiomyolipoma (HAML) from hepatocellular carcinoma (HCC). MethodsTwelve patients with HAML and 73 patients with HCC, whose diagnosis were pathologically confirmed at a single center in Japan between 2006 and 2016, were included in this study. The HAML and HCC cases were histologically evaluated and their histological growth patterns were compared. Using ultrasonographic data, we evaluated the imaging features representing the distinct histological differences. Ultrasonographic findings, reviewed by two examiners, were compared via interobserver variability analysis. This retrospective study was approved by the institutional ethics committee at our institute (No. 2017-1004). ResultsThe enrolled patients were carefully divided into two case sets: discovery case set (6 HAML patients and 37 HCC patients) and validation case set (6 HAML patients and 36 HCC patients). In the discovery case set, half of the HAML cases had intratumoral regions showing a reticular growth pattern. None of the HCC cases appeared as a region with the reticular growth pattern. The regions with the reticular growth pattern present as an intratumoral hyper echoic foci on ultrasound images. The presence of the intratumoral hyper echoic foci was significantly associated with HAML (P < .01). In the validation case set, the intratumoral hyper echoic foci predicted HAML at a specificity of 100% and a sensitivity of 50%. ConclusionsIntratumoral hyper echoic foci, representing reticular growth pattern, can be a promising ultrasonographic finding to help differentiate HAML from HCC.

Attenuation of light influences the size of Microcystis colonies

Colony formation provides excellent advantages for the dominance of Microcystis. However, studies on microenvironments during the process of colony formation are rare, especially regarding intra–colony light usage. This study analyzed the attenuation of light intensity in Microcystis colonies, where most objects followed Lambert-Beer law (I=I010-1.256×10-3bc). Intra–colony light limited the maximum thickness of the colony (BMax=4.3×105c−1) and thus affected colony size. Field data showed that the colony size for M. ichthyoblabe was small and limited to approximately 300 μm, while larger colonies were mainly formed by M. aeruginosa and M. wesenbergii respectively. These results imply that the strategies used by morphospecies to allow colonies to tolerate intra–colony light limitation might be different; M. aeruginosa benefited from a reticular growth pattern, and M. wesenbergii colonies were large (500 μm), obtaining a large thickness by lowering cell concentration. The results obtained in this work suggest that M. aeruginosa and M. wesenbergii had more advantages regarding intra–colony light usage, colony size level and bloom formation ability in summer and autumn.

HPV-Related Multiphenotypic Sinonasal Carcinoma: Four Cases that Expand the Morpho-Molecular Spectrum and Include Occupational Data

HPV-related multiphenotypic sinonasal carcinoma (HMSC) is a recently described distinct tumor entity of the sinonasal tract associated with high-risk subtypes of human papilloma virus (HPV), predominantly type 33. The biological behavior seems to be less aggressive than the often high-grade, highly proliferative morphology implies; however, recurrences are frequent. Most of the cases present as polypoid tumors within the nasal cavity. Microscopic morphology frequently encompasses adenoid cystic-like features or features reminiscent of other salivary gland tumors. Here, we describe four cases of this rare entity, all observed in women. The polypoid tumors were within the nasal cavity, leading to obstruction, facial pain and epistaxis. The morphology was predominantly basaloid, solid and adenoid cystic-like in two of four cases, one with additional glomeruloid features. Another case showed basaloid tumor cells with prominent mature squamous differentiation and extensive keratinization. A single case showed a predominantly solid and reticular growth pattern. All cases were diffusely positive for p16 (100%), expressed SOX10, LEF-1 and partially S-100, and harbored HPV high-risk types 33, 56 (2×) and 82. No recurrences or metastases were detectable after 3-50months of follow-up. Of note, three of four patients were nurses/nursing assistant. We expand the morphological spectrum by describing a glomeruloid growth pattern and extensive mature keratinization, and add HPV type 82 to the molecular spectrum. The finding of HMSC among predominantly nurses in our cohort warrants further epidemiological studies in larger cohorts.

Ectomesenchymal Chondromyxoid Tumor: A Neoplasm Characterized by Recurrent RREB1-MKL2 Fusions.

Ectomesenchymal chondromyxoid tumor is a rare and benign neoplasm with a predilection for the anterior dorsal tongue. Despite morphologic heterogeneity, most cases are characterized by a proliferation of bland spindle cells with a distinctive reticular growth pattern and myxoid stroma. The immunophenotype of these neoplasms is likewise variable; most cases express glial fibrillary acid protein and S100 protein, with inconsistent reports of keratin and myoid marker expression. The molecular pathogenesis is poorly understood; however, a subset of cases has been reported to harbor EWSR1 gene rearrangement. Following identification of an RREB1-MKL2 fusion gene by RNA Sequencing in an index patient, a retrospective review of additional cases of ectomesenchymal chondromyxoid tumors was performed to better characterize the clinical, immunohistochemical, and molecular attributes of this neoplasm. A total of 21 cases were included in this series. A marked predisposition for the dorsal tongue was confirmed. Most cases conformed to prior morphologic descriptions; however, hypercellularity, hyalinized stroma, and necrosis were rare attributes not previously emphasized. The neoplastic cells frequently coexpressed glial fibrillary acid protein, S100 protein, keratin, smooth muscle actin, and/or desmin; a single case was found to contain significant myogenin expression. An RREB1-MKL2 fusion product was identified in 19 tumors (90%), a single tumor (5%) had an EWSR1-CREM fusion product, and the remaining case lacked any known fusion gene by RNA Sequencing. The latter 2 cases subtly differed morphologically from many in the cohort. This series illustrates that recurrent RREB1-MKL2 fusions occur in most, perhaps all, cases of ectomesenchymal chondromyxoid tumor.

Microcystic/reticular schwannoma of the adrenal gland: a case report and literature review

Microcystic/reticular schwannoma is a recently described, rare, distinctive histological variant of schwannoma with a predilection for the gastrointestinal tract [1]. Unlike classic Schwannoma, most microcystic/reticular Schwannoma had an incomplete fibrous capsule, two distinctly different areas - hypercellular areas and myxoid areas, Microcystic/reticular schwannoma occurs in the internal organs, especially in the digestive tract and a rare case occurs in the adrenal glands [1–3]. Herein, we report a case of microcystic/reticular schwannoma of the adrenal gland, in a 60-year-old male with 7.0 cm × 6.0 cm × 5 cm mass in the left adrenal gland. The tumor showed a vague multinodular appearance with a pushing border and arranged in a microcystic and reticular growth pattern with anastomosing and intersecting strands of spindle cells in a myxoid or collagenous/hyalinized stroma. Tumor cells showed diffuse nuclear and cytoplasmic positivity for S-100.

Myoepithelial carcinoma of the parotid gland: A case of adequate fine-needle aspiration cytology specimens rendering a conclusive diagnosis possible

An 80-year-old male presented with a history of a hard right parotid mass that had gradually increased in size, with subsequent facial paralysis. A fine-needle aspiration biopsy was performed. The cytologic specimens contained a substantial number of sheet-like clusters or small groups of a mixture of plasmacytoid, oval to spindled, or large epithelioid cells having hyperchromatic pleomorphic nuclei, abundant cytoplasm with occasional inclusion body-like materials, and prominent nucleoli, in a relatively clear background. We first interpreted it as a carcinoma, suggestive of myoepithelial differentiation. Radical parotidectomy was performed, and a gross examination of the neoplasm revealed a non-capsulated and ill-defined tumor lesion, with a grayish or yellowish cut surface, associated with fat invasion. On a microscopic examination, the tumor was predominantly composed of the solid proliferation of atypical cells including a mixture of oval to spindled, plasmacytoid, or epithelioid cells, often arranged in a trabecular and reticular growth pattern with patchy eosinophilic hyalinized stroma. Immunohistochemistry showed that the carcinoma cells were specifically positive for p63, cytokeratins, and vimentin. Finally, electron microscopy demonstrated that their phenotype was consistent with a myoepithelial origin containing many bundles of variably thin actin filaments. Therefore, we finally made a diagnosis of myoepithelial carcinoma, defined as the malignant counterpart of benign myoepithelioma. We should be aware that owing to its characteristic cytological features, cytopathologists may be able to make a correct diagnosis of myoepithelial carcinoma, based on multiple and adequate samplings.

Paget's disease of the vulva treated with imiquimod: case report and review of the literature

Background: Extramammary Paget's disease of the vulva (EPDV) is a rare adenocarcinoma in situ of the vulvar skin and is often resected with involved margins due to its reticular growth pattern. Adjuvant treatment with the immunomodulator imiquimod may be suitable to avoid repeated and mutilating surgery.

Mitotically active microglandular hyperplasia of the cervix: a case series with implications for the differential diagnosis.

Microglandular hyperplasia (MGH) is a benign proliferation of endocervical glands with relatively uniform columnar or cuboidal nuclei, and rare to absent mitoses. Endometrial adenocarcinomas with mucinous differentiation or a microglandular pattern can closely mimic MGH, often resulting in a diagnostic dilemma in small biopsy specimens. Rare unusual morphologic features-mild to moderate nuclear atypia, solid or reticular growth pattern, hobnail and signet ring cells-have been previously reported in MGH. We present 9 cases of unusual, mitotically active-between 5 and 11 mitotic figures per 10 HPF-MGH, all of which presented as endocervical polyps and had morphologic features otherwise typical of MGH. The patients' age ranged between 35 and 56 yr, 2 patients were postmenopausal. High-risk human papillomavirus status was available in 7 patients, all of which were negative. The Ki-67 proliferation index ranged between 1% and 15%, and all cases were negative for p16, carcinoembryonic antigen, and vimentin immunostains. The clinical follow-up ranged from 3 to 76.2 mo, with a median of 40.7 mo, all patients were doing well without evidence of endocervical or endometrial malignancy. In summary, this case series documents the presence of rare cases of MGH demonstrating significant mitotic activity (up to 11/10 HPF) without a negative impact on the clinical prognosis. Mitotic activity alone should be interpreted with caution in small biopsy specimens with microglandular growth pattern. Immunohistochemical stains, especially p16, carcinoembryonic antigen, and vimentin, may be helpful-in addition to the patient's clinical history and human papillomavirus status to rule out endocervical or endometrial malignancy.

Extraskeletal Myxoid Chondrosarcoma

Extraskeletal myxoid chondrosarcoma is a rare soft tissue tumor characterized by uniform spindle cells arranged in a reticular growth pattern in abundant myxoid stoma. Although originally believed to be a variant of chondrosarcoma, the World Health organization has classified it as a tumor of uncertain differentiation due to its lack of cartilaginous differentiation. A-79-year-old-male patient was operated with the complaints of the arm mass for 6-7 years and total excision performed. Histppathological investigation of the tumor showed oval and spindle uniform cells which were created cords and pseudoacini in myxoid stroma. This rare case was presented with it’s pathological features.

The prognostic value of architectural patterns in a study of 37 type AB thymomas

Spindle cell thymomas with prominent amount of lymphocytes are classified as WHO type AB tumors. However, there are architectural pattern differences in these tumors. We investigated the importance of architectural pattern in type AB thymomas in relation to prognostic value. Archival hematoxylin–eosin stained slides of 37 AB type thymomas were reviewed for the presence (type 1) or absence (type 2) of reticular growth pattern. Reticular growth pattern is defined as the presence of a network of elongated bland spindle cells separating nests of tumor cells admixed with lymphoid cells. The architectural patterns were correlated with tumor stage at diagnosis and presence or absence of recurrent disease. The analysis identified 18 cases of type 1 AB thymoma and 19 cases of type 2. Type 2 cases also had greater cytologic atypia within the spindle cells. Patients with type 1 tumors were more likely to have early stage disease. In contrast, type 2 pattern was associated with higher stage at diagnosis (P<0.001) and greater likelihood for recurrence (P<0.05) and metastases. Architectural features are prognostically relevant in classification of WHO AB type thymomas and may constitute a form of personalized medicine. Independent confirmation of the findings is necessary to confirm the association of architectural pattern with outcomes.

Myoepithelioma of Tongue

Myoepithelioma is a rare neoplasm of the salivary glands, generally occurring in the parotid gland and less often in the minor accessory salivary gland of the oral cavity. The histological appearance includes solid, myxoid and reticular growth patterns. Vimentin and S-100 protein are very sensitive but non-specific immunohistochemical markers of neoplastic myoepithelium. Conservative surgery is the treatment of choice. A case of myoepithelioma of the minor salivary gland of tongue is described, focusing on clinical behaviour, histopathological and immunohistochemical features.

Reticular angiomatoid “malignant” fibrous histiocytoma—a case report with cytogenetics and molecular genetic analyses

Angiomatoid "malignant" fibrous histiocytoma is a rare sarcoma of low malignant potential that occurs most commonly in the extremities of children and young adults. Herein, we present a case of angiomatoid malignant fibrous histiocytoma with unusual histologic features arising in the mediastinum of an 80-year-old man. The tumor exhibited a reticular growth pattern and myxoid stroma. The tumor cells expressed epithelial membrane antigen and desmin. Cytogenetic analysis revealed the translocation t(2;22)(q33;q12). Molecular genetic analysis confirmed the rearrangement of the EWSR1 locus and the presence of the EWSR1/CREB1 fusion. This report expands the clinicopathologic spectrum of angiomatoid malignant fibrous histiocytoma and underscores the value of integrating morphologic, immunophenotypic, and molecular findings in the identification of its unusual morphologic variants.

Reticular perineurioma: a distinctive variant of soft tissue perineurioma.

Soft tissue perineurioma is a relatively recently characterized, uncommon tumor composed of perineurial cells exhibiting immunoreactivity for epithelial membrane antigen (EMA). These lesions occur preferentially in adults and may arise in a wide variety of anatomic sites. We report the clinicopathologic, immunohistochemical, and ultrastructural features of six cases of a poorly recognized morphologic variant of soft tissue perineurioma, characterized by a highly distinctive reticular growth pattern. Four of the patients were women, two were men (age range, 34-61 yrs; median, 43 yrs). Four of the cases arose in the subcutis of the upper extremity; three were located distally (thumb, finger, palm), whereas one was situated more proximally near the elbow region. One case each was located in the gingiva and subcutaneous tissue of the inguinal region, respectively. In those cases in which clinical information was available (n = 5), the lesions were asymptomatic and had been present from 4 months to 10 years before resection. Tumor size ranged from 1.5 cm to 10 cm (median size, 4.25 cm). Microscopically the lesions demonstrated a predominantly lace-like or reticular growth pattern composed of anastomosing cords of fusiform cells with bipolar cytoplasmic processes and palely eosinophilic cytoplasm. Nuclei were centrally placed, ovoid to fusiform in shape, and no mitoses were seen. Transition to more cellular areas was focally present in all cases. The stroma was variably collagenous to myxoid. Immunohistochemically all six cases stained positively for EMA but not for S-100 protein. Two cases demonstrated focal positive cytoplasmic staining for cytokeratin, whereas one case was focally desmin positive. Ultrastructural examination of two tumors showed typical features of perineurial cells. Follow up (available in only two cases) showed no evidence of recurrence. Reticular perineurioma of soft tissue represents an unusual morphologic variant within the perineurioma group, which should be distinguished from myoepithelial tumors, extraskeletal myxoid chondrosarcoma, and myxoid synovial sarcoma.

Benign myoepithelioma of the salivary glands: a true entity?

Myoepithelioma is a rare neoplasm of the salivary glands which is now recognized as an individual entity in the revised WHO classification. In this study, eleven benign tumours are presented. Most patients gave a history of a slowly enlarging mass, which was cured by surgical excision. However, one case recurred several times over 50 years, and another still has residual tumour and removal is not possible. The histological appearances included solid, myxoid and reticular growth patterns, composed predominantly of spindle shaped or plasmacytoid (hyaline) cells. Many of the tumours also contained occasional small ducts. All 11 tumours were positive for S-100 protein, variable reactions being seen for various other antigens--keratins, human milk fat globulin, carcinoembryonic antigen, alpha smooth muscle actin and vimentin. It is probable that myoepithelioma constitutes one end of a biological spectrum which also includes pleomorphic adenoma and some (non-membranous) basal cell adenomas. In practice, however, we still advocate retention of myoepithelioma as a separate diagnostic category, on the grounds that it has a range of distinctive microscopic appearances and poses its own unique problems in correct identification.

The effect of endothelial cell proliferation in vitro

The proliferation of bovine aortic endothelial cells is highly stimulated by using a plasma clot instead of glass or plastic as a substrate. The cells form a dense monolayer which is usually under grown by a second layer of endothelial cells showing a more reticular growth pattern. When endothelial cells attached to a plasma clot are covered with a second layer of coagulated plasma, the cells arrange to shapes which bear a great resemblance to capillary structures. It seems that this endothelial cell property is only expressed when the entire cell surface is forced to interact with a surrounding adhesive matrix.

Endodermal sinus tumor of the mediastinum: A report of seven cases and review of the literature

Primary mediastinal endodermal sinus tumor is rare, and to date only 49 cases have been described in the English-language literature. Seven new cases are reported. Light microscopic examination showed characteristic features including papillary, reticular, tubular and solid growth patterns, complete or incomplete Schiller-Duval bodies and intracellular or extracellular periodic acid-Schiff-positive material. Immunohistochemical studies showed alpha-1-antitrypsin in seven, alpha-fetoprotein in seven, keratin in six, and carcinoembryonic antigen in four cases. The beta subunit of human chorionic gonadotropin, albumin, fibronectin, and transferrin were not found in any case. Electron microscopic studies performed in four cases showed intracellular and extracellular basement membrane-like material, multiple large multivesicular bodies, desmosomes and microvilli. Mediastinal endodermal sinus tumor can and must be differentiated from poorly differentiated adenocarcinoma metastatic or extending to the mediastinum because of the distinctly different prognoses and therapies. In spite of modern chemotherapy, the prognosis of mediastinal endodermal sinus tumor remains poor. The single most important prognostic indicator is whether the tumor mass can be completely excised before or after chemotherapy.