Palisade (pathology): Difference between revisions - Wikipedia

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{{Short description|Microscopic view of single layer of cells}}

[[File:Ameloblastoma_-_high_mag.jpg|thumb|[[Micrograph]] of an [[ameloblastoma]] showing characteristic palisading. [[H&E stain]].]]

In [[histopathology]], a '''palisade''' is a single layer of relatively long cells, arranged loosely perpendicular to a surface and parallel to each other.<ref>{{cite web|url=https://medical-dictionary.thefreedictionary.com/palisading|title=palisading|website=[[The Free Dictionary]] by Farlex, citing Segen's Medical Dictionary, copyrighted 2012|access-date=2019-09-11}}</ref> A '''rosette''' is a palisade in a halo or spoke-and-wheel arrangement, surrounding a central core or hub.<ref name="Ahmed2017"/> A '''pseudorosette''' is a perivascular radial arrangement of [[neoplastic]] cells around a small blood vessel.<ref name="Ahmed2017"/> Rosettes are characteristic of [[tumor]]s.

==Rosette==

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===Pathogenesis===

Rosettes may be considered primary or secondary manifestations of tumor architecture. Primary rosettes form as a characteristic growth pattern of a given tumor type whereas secondary rosettes result from the influence of external factors on tumor growth. For example, in the latter instance, regressive cell swelling may centripetally displace the cytoplasm as the nucleus is squeezed to the periphery, forming a secondary rosette. Although the presence of primary rosettes may suggest a given diagnosis, usually this finding alone is not considered absolutely pathognomic[[pathognomonic]] for one specific tumor type.<ref name="Ahmed2017"/>

Loss or gain of genetic information is the main cause of rosette and pseudorosette formation. The cell populations exhibiting neuronal differentiation are believed to secrete surface glycoproteins and glycolipids which mediate cell-to-cell recognition and adhesion. One hypothesis is that these sticky cell surface markers cause the developing cell bodies to cluster or aggregate and their primitive neurites to tangle. As the cells grow, the neurite tangle remains centrally located and the cell bodies are squeezed to the periphery, thus explaining the rosette pattern. Depending upon their location, ependymal[[ependyma]]l cells may display 2 cell poles. A luminal pole projects to the ependymal lining of a ventricle and a "submesenchymal pole" projects toward the surface of the brain demonstrating glial processes and peripherally situated footplates. Frieda and Pollak conceptualize the architecture of [[ependymoma]]s as a primitive [[neural tube]] turned inside out with the submesenchymal poles converging toward a central vessel, thus forming a pseudorosette rather than projecting centrifugally toward the [[Pia mater|pia]].<ref name="Ahmed2017"/>

to the ependymal lining of a ventricle and a “submesenchymal pole” projects toward the surface of the brain demonstrating glial processes and peripherally situated footplates. Frieda and Pollak conceptualize the architecture of ependymomas as

a primitive neural tube turned inside out with the submesenchymal poles converging toward a central vessel, thus forming a pseudorosette rather than projecting centrifugally toward the pia.<ref name="Ahmed2017"/>

===Causes===

True rosettes are mainly found in neuropathologic disorder. andOther areconditions alsowhere they are present ininclude [[osteosarcoma]], [[non-Hodgkin lymphoma]], [[fibromyxoid sarcoma]], [[medullary thyroid carcinoma]], [[embryonal tumor]] with abundant neuropil and true rosettes (ETANTR), rhambdomyosarcoma[[rhabdomyosarcoma]], chronic [[cholestasis]] and chronic active [[hepatitis]], tobacco rosette: complex viral disease, malaria, [[adenocarcinoma]] in colon and rectum<!-- in the Aghamiri population -->, hyalinizing spindle cell fused with giant rosette, and [[endometrial stromal sarcoma]] with hyalinizing giant rosettes.<ref name="Ahmed2017"/>

Aghamiri population, hyalinizing spindle cell fused with giant rosette, endometrial stromal sarcoma with hyalinizing giant rosettes, embryonal tumor etc.<ref name="Ahmed2017"/>

[[Flexner–Wintersteiner rosette]]s (spoke-and-wheel shaped [[cell (biology)|cell]] formation seen mainly in [[retinoblastoma]]<ref name="thefreedictionary.com">[http://medical-dictionary.thefreedictionary.com/Flexner-Wintersteiner+rosette Definition of 'rosette'], from The Free Dictionary. Retrieved 6 January 2010.</ref>) have been described as a form of palisading.<ref>[https://books.google.com/books?id=V5Snw0Q8LrEC&pg=PA666 page 666] in: {{cite book|title=Head and Neck Surgical Pathology|author=Ben Z. Pilch|publisher=Lippincott Williams & Wilkins|year=2001|isbn=9780397517275}}</ref>

===Flexner–Wintersteiner rosette===

[[Image:Retinoblastoma rosette.jpg|thumb|'''Flexner–Wintersteiner rosettes''' in [[Retinoblastoma]].]]

A ''[[Flexner–Wintersteiner rosette'' is]]s, a spoke-and-wheel shaped cell formation seen in [[retinoblastoma]] and certain other [[Ophthalmology|ophthalmic]] [[tumor]]s.tumors,<ref name="thefreedictionary.com">[http://medical-dictionary.thefreedictionary.com/Flexner-Wintersteiner+rosette Definition of 'rosette'], from The Free Dictionary. Retrieved 6 January 2010.</ref>) have been described as a form of palisading.<ref>[https://books.google.com/books?id=V5Snw0Q8LrEC&pg=PA666 page 666] in: {{cite book|title=Head and Neck Surgical Pathology|author=Ben Z. Pilch|publisher=Lippincott Williams & Wilkins|year=2001|isbn=9780397517275}}</ref>

Unlike the center of the [[Homer-Wright rosette|Homer Wright rosette]], the central lumen is devoid of fiber-rich [[neuropil]]. The defining feature of this rosette is the central extension of cytoplasmic projections of the surrounding cells. Like the Homer Wright rosette, the Flexner–Wintersteiner rosette represents a specific form of tumor differentiation.<ref name="McLean">McLean IW, Burnier MN, Zimmerman LE, et al. Tumors of the retina. In: Atlas of tumor pathology: tumors of the eye and ocular adnexa. Washington, DC: Armed Forces Institute of Pathology; 1994:97–154</ref><ref>Donoso LA, Shields CL, [[Eva Y.-H. P. Lee|Lee EY-H.]] Immunohistochemistry of retinoblastoma. Ophthal Paediatr Genet 1989;10:3–32</ref><ref>Vrabec T, Arbizo V, Adamus G, et al. Rod cell-specific antigens in retinoblastoma. Arch Ophthalmol 1989;107:1061–63</ref><ref>Kivela T. Glycoconjugates in retinoblastoma: a lectin histochemical study of ten formalin-fixed and paraffin embedded tumours. Virchows Arch A 1987;410:471–79</ref> [[Electron microscopy]] reveals that the tumor cells forming the Flexner–Wintersteiner rosette have ultrastructural features of primitive photoreceptor cells.<ref>Ts’o MOM, Fine BS, Zimmerman LE. The Flexner–Wintersteiner rosettes in retinoblastoma. Arch Pathol 1969;88:664–71</ref> Furthermore, the rosette lumen shows similar staining patterns as in [[Photoreceptor cells|rods and cones]],<ref>Zimmerman LE. Retinoblastoma and retinocytoma. In: Spencer WH, ed. Ophthalmic pathology: an atlas and textbook. Philadelphia: WB Saunders; 1985:1292–351</ref> suggesting that Flexner–Wintersteiner rosettes represent a specific form of retinal differentiation. In addition to being a characteristic finding in retinoblastomas, Flexner–Wintersteiner rosettes may also be found in [[pinealoblastoma]]s and [[medulloepithelioma]]s.<ref name="McLean"/>

<gallery mode="packed" heights="170">

File:Structure of a Flexner–Wintersteiner rosette.jpg|Structure of a Flexner–Wintersteiner rosette

</gallery>

Flexner–Wintersteiner rosettes were first described in 1891 by [[Simon Flexner]] (1863–1946), a physician, scientist, administrator, and professor of experimental [[pathology]] at the [[University of Pennsylvania]] (1899–1903). Flexner noted characteristic clusters of cells in an infantile [[Ocular oncology|eye tumor]] which he called retinoepithelioma.<ref>Flexner S. A peculiar glioma (neuroepithelioma?) of the retina. Johns Hopkins Hosp Bull 1891;2:115–19</ref><ref>Schatski SC. Simon Flexner. AJR Am J Roentgenol 1997;169:1395–96.</ref><ref>Bendiner E. Simon Flexner: his "rock" was for the ages. Hosp Pract 1988;23:213–66</ref> A few years later, inIn 1897, [[Austrians|Austrian]] [[ophthalmologist]] [[Hugo Wintersteiner]] (1865–1946) confirmed Flexner's observations and noted that the cell clusters resembled rods and cones.<ref>Wintersteiner H. Die zellenZellen der geschwulstGeschwulst. In: Das neuroepitheliomaneuroëpithelioma retinae: Eine anatomische und klinisheklinische studieStudie. Leipzig: Franz Deuticke; 1897:12–16</ref> These characteristic rosette formations were subsequently recognized as important features of retinoblastomas.

==Pseudorosette==

A ''pseudorosette'' is a perivascular radial arrangement of neoplastic cells around a small blood vessel. Pseudorosettes are present in [[neuroblastoma]], [[medulloblastoma]], [[malignant melanoma]], [[ependymoma]], [[Merkel cell carcinoma]], [[neuroendocrine tumor]] of the skin, [[seborrheic keratosis]], dendritic cell [[neurofibroma]], [[astroblastoma]], [[Large-cell neuroendocrine cancer|large cell neuroendocrine tumor]] of the cervix, clear cell ependymoma of the spinal cord, [[celiac disease]], nasal tumor of olfactory origin, rosette -forming glioneural tumor (RGNT), [[oncocytoma]], [[Wilm's tumor]], and [[pheochromocytoma]] of the urinary bladder.<ref name="Ahmed2017"/>

===Homer -Wright pseudorosette===

[[File:Micrograph of Homer Wright pseudorosettes.jpg|thumb|Micrograph of Homer -Wright pseudorosettes]]

A ''Homer -Wright pseudorosette'' is a type of pseudorosette in which differentiated tumor cells surround the [[neuropil]].<ref name="Wippold & Franz, 2006">{{cite journal|last1=Wippold II|first1=Franz J.|last2=Perry|first2=A.|title=Neuropathology for the Neuroradiologist: Rosettes and Pseudorosettes|journal=American Journal of Neuroradiology|date=March 2006|volume=27|issue=3|pages=488–492|pmid=16551982|pmc=7976948 |url=http://www.ajnr.org/content/27/3/488.full|access-date=26 August 2015}}</ref> Examples of tumors containing these are [[neuroblastoma]], [[medulloblastoma]], [[pinealoblastoma]], and [[primitive neuroectodermal tumor]]s of bone. Homer -Wright rosettes are considered "pseudo" in the sense that they are not true rosettes. True rosettes areUnlike [[Flexner–Wintersteiner rosette]]s, which contain an empty lumen., Homer -Wright rosettes contain abundant fibrillary material. They are named for [[James Homer Wright]].

<gallery mode="packed" heights="170">

File:Structure of a Homer Wright pseudorosette.jpg|Structure of a Homer -Wright pseudorosette

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===Pineocytomatous/neurocytic pseudorosettes===

Histologic features of these two tumors are virtually identical, including their tendency to form neuropilrichneuropil-rich rosettes, referred to as pineocytomatous/neurocytic rosettes in central neurocytoma. Both are quite similar to the Homer -Wright rosette, but they are generally larger and more irregular in contour. The cells of the pineocytomatous/neurocytic rosettes are also considered to be much more differentiated than the cells forming Homer -Wright rosettes in that the nuclei are slightly larger, more rounded, much less mitotically active, and paler or less hyperchromatic. In rare cases, these rosettes may aggregate in a sheet of back-to-back clusters resembling field stonefieldstone pavement.<ref name="Ahmed2017"/>

<gallery mode="packed" heights="170">

File:Micrograph of pineocytomatous-neurocytic pseudorosettes.jpg|Micrograph of pineocytomatous/neurocytic pseudorosettes

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==Clinical significance of rosettes and pseudorosettes==

The neuropathologic diagnosis of brain tumors entails the microscopic examination of conventional formalin-fixed paraffin-embedded tissue samples surgically removed from a radiographically defined lesion. Pathologists rely on visual clues such as pattern recognition when examining the stained tissue with a microscope, much as radiologists rely on grayscale patterns of densities and intensities on images. Some histologic patterns of cellular architecture are distinctive if not pathognomonic whereas others are less specific, but nevertheless considerably narrow the differential diagnosis. The precise biologic bases for some of the observed microscopic patterns are poorly understood though their recognition is nonetheless useful. Rosettes are a commonly encountered neuropathologic histologic architectural pattern seen within certain tumors is the rosette. Although more advanced methods of tissue examination have been developed, such as histochemical and immunohistochemical profiling, genetic analysis, and electron microscopy, the microscopic review of [[H&E stain]]ed material remains a critical component of tumor diagnosis.<ref name="Ahmed2017"/>

less specific, but nevertheless considerably narrow the differential diagnosis. The precise biologic bases for some of the observed

microscopic patterns are poorly understood though their recognition remains useful nonetheless. One commonly encountered neuropathologic histologic architectural pattern seen within certain tumors is the rosette. The purpose of this report is to review

the patterns of rosettes and pseudorosettes in the context of such tumors as medulloblastoma/primitive neuroectodermal tumor (PNET),

retinoblastoma, ependymoma, central neurocytoma and pineocytoma.<ref name="Ahmed2017"/>

More advanced methods of tissue examination such as histochemical and immunohistochemical profiling, genetic analysis, and electron microscopy have been developed, the microscopic review of H&E stained material remains a critical component of tumor diagnosis. Immunohistochemical evidence of neuronal differentiation is found in nearly all cases with neuronal markers such as synaptophysin, neuronspecific enolase, and neurofilament protein. Some medulloblastomas may also display other forms of differentiation as demonstrated by the presence of the astrocytic marker glial fibrillary acidic protein. Skeletal muscle and melanocytic differentiation are considerably less common and define the medullomyoblastoma and melanotic medulloblastoma variants, respectively.<ref name="Ahmed2017"/>▼

==Methods for diagnosis of rosettes and pseudorosettes==

▲More advanced methods of tissue examination such as histochemical and immunohistochemical profiling, genetic analysis, and electron microscopy have been developed, the microscopic review of H&E stained material remains a critical component of tumor diagnosis. Immunohistochemical evidence of neuronal differentiation is found in nearly all cases with neuronal markers such as synaptophysin, neuronspecific enolase, and neurofilament protein. Some medulloblastomas may also display other forms of differentiation as demonstrated by the presence of the astrocytic marker glial fibrillary acidic protein. Skeletal muscle and melanocytic differentiation are considerably less common and define the medullomyoblastoma and melanotic medulloblastoma variants, respectively.<ref name="Ahmed2017"/>

==Long palisades==

[[File:Palisading in basal cell cancer.jpg|thumb|Palisading in nodular [[basal-cell carcinoma]].]]

Palisades that are generally longer than a rosette or pseudorosette can be seen in neural tumors such as [[Schwannoma]],<ref>{{cite journal |vauthors=Wippold FJ, Lämmle M, Anatelli F, Lennerz J, Perry A |title=Neuropathology for the neuroradiologist: palisades and pseudopalisades |journal=AJNR Am J Neuroradiol |volume=27 |issue=10 |pages=2037–41 |date=2006 |pmid=17110662 |pmc=7977220 }}</ref><ref>{{cite journal |vauthors=Kadono T, Okada H, Okuno T, Ohara K |title=Basal cell carcinoma with neuroid type nuclear palisading: a report of three cases |journal=Br. J. Dermatol. |volume=138 |issue=6 |pages=1064–6 |date=June 1998 |pmid=9747376 |doi=10.1046/j.1365-2133.1998.02281.x |s2cid=20339424 }}</ref> as well as in [[ameloblastoma]]s. ItThey can also be seen in nodular [[basal-cell carcinoma]]s.<ref name="PaolinoDonati2017">Initially copied from: {{cite journal|last1=Paolino|first1=Giovanni|last2=Donati|first2=Michele|last3=Didona|first3=Dario|last4=Mercuri|first4=Santo|last5=Cantisani|first5=Carmen|title=Histology of Non-Melanoma Skin Cancers: An Update|journal=Biomedicines|volume=5|issue=4|year=2017|pages=71|issn=2227-9059|doi=10.3390/biomedicines5040071|pmid=29261131|pmc=5744095|doi-access=free}}</ref>

==Visually similar findings==