Pituitary adenoma classification

Pituitary adenoma classification

They are classified based on size or cell of origin. Pituitary adenoma can be described as microadenomamacroadenoma, and giant tumors based on size. Microadenoma is tumors less than 10 mm, while macroadenoma includes tumors larger than 10mm. Giant pituitary adenomas are more than 40 mm. There are functional pituitary adenomas in which the cell type that composes them causes increased secretion of one or multiple hormones of the anterior pituitary. Alternatively, there are Non-Functioning Pituitary Adenomas that do not secrete hormones, but they can compress the surrounding areas of the anterior pituitary leading to hormonal deficiencies 1).

see The 2017 World Health Organization classification of tumors of the pituitary gland.

In the fourth edition of the World Health Organization classification of endocrine tumors, are two critical changes to the classification for pituitary adenomas.

One is that the term “atypical adenoma,” which was characterized based on highly proliferative properties to predict adenomas that carry a poor prognosis, was completely eliminated due to the lack of definitive evidence. The other change is the introduction of more precise cell lineage-based classification of pituitary adenoma that is defined based on lineage-specific transcription factors and hormones produced. Accordingly, null cell adenomas have been re-defined as those that show completely negative immunostaining either for hormones or for adenohypophyseal transcription factors 2).

Somatotroph adenoma.

Lactotroph adenoma.

Tyrotroph adenoma.

Corticotroph adenoma.

Gonadotroph adenoma.

Null cell adenoma

Plurihormonal pituitary adenoma and double adenomas.


The classification is based upon the size, invasion of adjacent structures, sporadic or familial cases, biochemical activity, clinical manifestations, morphological characteristics, response to treatment, and recurrence 3).

Current classification systems for PAs are based primarily on secretory characteristics of the tumor but are also classified on the basis of phenotypical characteristics, including tumor size, degree of invasiveness (e.g., Knosp grade), and immunohistological findings 4).

The anterior WHO classification system for PAs was refined to include designations for benign adenoma, atypical adenoma, and pituitary carcinoma on the basis of p53 immunoreactivity, MIB-1 indexmitotic activity, and the absence/presence of metastases 5) 6).

These tumor types can be microadenomas or macroadenomas and can either be functional or non-functional.

By Size

Pituitary microadenoma

Pituitary macroadenoma

Giant pituitary adenoma

Volume can be calculated using MRI-guided volumetrics and an ellipsoid approximation (TV × AP × CC/2) transverse (TV), antero-posterior (AP) and cranio-caudal (CC).

By Function

Functioning pituitary adenoma

Nonfunctioning pituitary adenoma

Pituitary adenomas with gangliocytic component are rare tumors of the sellar region that are composed of pituitary adenoma cells and a ganglion cell component. Their histogenesis and hence nosology is not yet resolved because of the small number of cases reported and lack of large series in the literature 7).

Invasive pituitary adenomas and pituitary carcinomas are clinically indistinguishable until the identification of metastases.

Consistency

Although most authors differentiate easily aspirated (soft) tumors from those that are not (fibrous, might require prior fragmentation), there is no universally accepted PA consistency classification. Fibrous PA tends to be hypointense on T2WI and has lower apparent diffusion coefficient (ADC) values. Fibrous tumors seemed to present higher invasion into neighboring structures, including the cavernous sinus. Several articles suggest that dopamine agonists could increase PA consistency and that prior surgery and radiotherapy also make PA more fibrous. The anatomopathological studies identify collagen as being mainly responsible for fibrous consistency of adenomas.

Conclusions: Preoperative knowledge of PA consistency affords the neurosurgeon substantial benefit, which clearly appears to be relevant to surgical planning, risks, and surgery outcomes. It could also encourage the centralization of these high complexity tumors in reference centers. Further studies may be enhanced by applying standard consistency classification of the PA and analyzing a more extensive and prospective series of fibrous PA. 8).

Knosp Grade.

Hardy’s Classification of Pituitary Adenomas.


1)

Russ S, Shafiq I. Pituitary Adenoma. 2020 Feb 4. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from http://www.ncbi.nlm.nih.gov/books/NBK554451/ PubMed PMID: 32119338.
2)

Inoshita N, Nishioka H. The 2017 WHO classification of pituitary adenoma: overview and comments. Brain Tumor Pathol. 2018 Apr;35(2):51-56. doi: 10.1007/s10014-018-0314-3. Epub 2018 Apr 23. Review. PubMed PMID: 29687298.
3)

Syro LV, Rotondo F, Ramirez A, Di Ieva A, Sav MA, Restrepo LM, Serna CA, Kovacs K. Progress in the Diagnosis and Classification of Pituitary Adenomas. Front Endocrinol (Lausanne). 2015 Jun 12;6:97. doi: 10.3389/fendo.2015.00097. eCollection 2015. Review. PubMed PMID: 26124750; PubMed Central PMCID: PMC4464221.
4)

Knosp E, Steiner E, Kitz K, Matula C: Pituitary adenomas with invasion of the cavernous sinus space: a magnetic resonance imaging classification compared with surgical findings. Neurosurgery 33:610–618, 1993
5)

Barnes L, Eveson JW, Reichart P, David Sidransky: World Health Organization Classification of Tumours: Pathology and Genetics of Head and Neck Tumours Lyon, IARC Press, 2005
6)

Zada G, Woodmansee WW, Ramkissoon S, Amadio J, Nose V, Laws ER Jr: Atypical pituitary adenomas: incidence, clinical characteristics, and implications. J Neurosurg 114:336–344, 2011
7)

Balci S, Saglam A, Oruckaptan H, Erbas T, Soylemezoglu F. Pituitary adenoma with gangliocytic component: report of 5 cases with focus on immunoprofile of gangliocytic component. Pituitary. 2014 Jan 16. [Epub ahead of print] PubMed PMID: 24430434.
8)

Acitores Cancela A, Rodríguez Berrocal V, Pian H, Martínez San Millán JS, Díez JJ, Iglesias P. Clinical relevance of tumor consistency in pituitary adenoma. Hormones (Athens). 2021 Jun 19. doi: 10.1007/s42000-021-00302-5. Epub ahead of print. PMID: 34148222.

Anterior transpetrosal approach

Anterior transpetrosal approach

see Anterior petrosectomy.

In 1985Takeshi Kawase from the Department of Neurosurgery, Keio University School of Medicine, Tokyo, and Ashikaga Red Cross Hospital, AshikagaJapan 1) published an anterior petrosal approach to expose the posterior cranial fossa and to minimize retraction of the temporal lobe for upper petroclival


Anterior subtemporal and transpetrous apex approaches let us some exposure of deep region, however they require an unacceptable temporal lobe retraction and provide an extremely narrow surgical corridor in cases of large tumors mainly located in the infratentorial space 2) 3).

This approach requires epidural subtemporal procedures to expose the petrous apex adequately. The petrous apex must be totally resected and the dura of the temporal lobe and posterior fossa is then cut to ligate the superior petrosal sinus and tentorium. In this procedure, the most important things are to preserve the internal carotid artery (C2 segment) and greater superficial petrosal nerve (GSPN). To identify the GSPN, facial nerve integrity monitor (Medtronic Inc, Dublin, Ireland) is very useful. In the extradural bone removal, Sonopet Ultrasonic Aspirator (Stryker Ltd, Portage, Michigan) is a very excellent surgical tool for avoiding the injury of the internal carotid artery. As demonstrated by Cavalcanti, ATPA is particularly useful for accessing lesions located in the upper ventral pons via the supratrigeminal zone because it provides a wide and shallow surgical field above the trigeminal nerve without requiring retraction of the cerebellum 4).


Several neurosurgeons still have difficulty with removing tumors through an anterior petrosal approach, because a complete understanding of the Kawase pyramid has not been achieved. Jung et al. hypothesized that if anterior petrosectomy is performed with a three-dimensional understanding of the Kawase pyramid, it would have a positive effect on the extent of tumor resection.

They performed a retrospective study of patients who underwent surgical treatment for meningioma through an anterior petrosal approach. Patients were divided into total resection and subtotal resection groups, and statistical differences between the two groups were analyzed. To identify factors predictive of complete tumor removal, univariable and multivariable logistic regression analyses were performed.

The width and height of the drilled internal acoustic canal (IAC) of the total resection group were significantly longer than those of the subtotal resection group (p=0.001, p=0.033). The operative angle of the total resection group was significantly larger than that of the subtotal resection group (p<0.001). Regression analyses showed only drilled IAC width to be predictive of complete tumor removal, increasing the likelihood thereof by 2.778-fold with an increase in drilled IAC width by 1 mm (p=0.023).

Insufficient petrosectomy during an anterior petrosal approach adversely affects the extent of tumor resection. Furthering a three-dimensional understanding of the Kawase pyramid could help complete tumor resection and better outcomes without causing damage to the surrounding organs 5).


see Anterior transpetrosal transtentorial approach.

see Anterior transpetrosal approach indications.

A study of Shibao et al., included 126 patients treated via the ATPA. The bridging vein (BV) and the tentorial sinus (TenS) located in the operative fields were analyzed. Furthermore, in the preoperative evaluation, the cross-sectional shapes of the intradural vein and the interdural sinus were analyzed by curved planar reconstruction (CPR), and the flattening rate was calculated. Flattening rate = (a-b)/a = 1-b/a (a: long radius, b: short radius).

Seventeen BVs and 18 TenS were identified. The bridging site was divided into two groups: tentorial and middle fossa. The middle fossa group was divided into three subgroups: cavernous sinus, middle fossa dural sinus, and middle fossa dural adherence. Five isolated TenS were sacrificed and no venous complications were observed. The mean flattening rate was 0.13 in the intradural vein and 0.51 in the interdural sinus, respectively (P = 0.0003).

They showed classification of the BV, and preservation of the BV and TenS during the ATPA. Furthermore, they found that the interdural sinus was significantly flatter than the intradural veins. Measuring the flattening rate by CPR may be useful to identify BVs preoperatively 6).


1)

Kawase T, Toya S, Shiobara R, Mine T. Transpetrosal approach for aneurysms of the lower basilar artery. J Neurosurg. 1985 Dec;63(6):857-61. PubMed PMID: 4056899.
2)

Bambakidis NC, Gonzalez LF, Amin‐Hanjani S, et al: Combined skull base approaches to the posterior fossa. Technical note. Neurosurg Focus 19:E8, 2005
3)

Yang J, Ma SC, Fang T, et al: Subtemporal transpetrosal apex approach: study on its use in large and giant petroclival meningiomas. Chin Med J (Engl) 124:49‐55, 2011
4)

Yokoyama K, Kawanishi M, Sugie A, Yamada M, Tanaka H, Ito Y, Yamshita M. Microsurgical Resection of a Ventral Pontine Cavernoma via Supratrigeminal Zone by Anterior Transpetrosal Approach: 2-Dimensional Operative Video. Oper Neurosurg (Hagerstown). 2018 Jul 19. doi: 10.1093/ons/opy177. [Epub ahead of print] PubMed PMID: 30032310.
5)

Jung IH, Yoo J, Roh TH, Park HH, Hong CK. Importance of sufficient petrosectomy in an anterior petrosal approach relightening of the Kawase pyramid. World Neurosurg. 2021 May 15:S1878-8750(21)00712-9. doi: 10.1016/j.wneu.2021.05.017. Epub ahead of print. PMID: 34004357.
6)

Shibao S, Toda M, Fujiwara H, Jinzaki M, Yoshida K. Bridging vein and tentorial sinus in the subtemporal corridor during the anterior transpetrosal approach. Acta Neurochir (Wien). 2019 Feb 23. doi: 10.1007/s00701-019-03857-w. [Epub ahead of print] PubMed PMID: 30798482.

Rosai-Dorfman disease

Rosai-Dorfman disease

Sinus histiocytosis or Rosai-Dorfman disease (RDD) is a rare but well-recognized disorder characterized by an unusual proliferation of histiocytic cells. Intracranial localization is a rare manifestation of RDD.

Rosai-Dorfman disease (RDD) is a rare disease that can be triggered by either viral or bacterial infection. Several parts of the body can be involved, from the CNS to the pelvic regions had been reported.

Conventional MRI, combined with diffusion-weighted imaging and ADC mapping, is an important diagnostic tool in evaluating RDD patients. An accurate diagnosis of RDD should consider the clinical features, imaging characteristics, and the pathological findings 1).


FDG-PET/CT image of a cystic central nervous system Rosai-Dorfman disease 2).

Meningioma.

Rosai-Dorfman disease: especially if extracranial lesions are also identified. Usually in young adults. Isolated intracranial involvement is rare. MRI: duralbased enhancing mass with signal characteristics similar to meningioma, may have dural tail. Most common intracranial locations: cerebral convexities, parasagittal, suprasellar, cavernous sinus. Pathology: dense fibrocollagenous connective tissue with spindle cells and lymphocytic infiltration, stains for CD68 & S-100. Histiocytic proliferation without malignancy. Foamy histiocytes are characteristic. Surgery and immunosuppressive therapy not effective. Low-dose XRT may be the best option.


Some case reports highlights the necessity to consider Rosai-Dorfman disease as a potential posterior fossa tumor differential diagnosis and/or intraventricular tumor.

At present, there is a serious lack of guidelines as to how to treat cases of RDD involving the spine. Current trends show that surgery remains the first method of choice to cure this disease, but in refractory or recurrent RDD, repeat surgery cannot guarantee total resection. Under such circumstances, adjuvant therapy can be very useful.

Rosai-Dorfman disease case reports.


1)

Cheng X, Cheng JL, Gao AK. A Study on Clinical Characteristics and Magnetic Resonance Imaging Manifestations on Systemic Rosai-Dorfman Disease. Chin Med J (Engl). 2018 Feb 20;131(4):440-447. doi: 10.4103/0366-6999.225053. PubMed PMID: 29451149; PubMed Central PMCID: PMC5830829.
2)

Kong Z, Wang Y, Ma W, Cheng X. FDG-PET/CT image of a cystic central nervous system Rosai-Dorfman disease. Eur J Nucl Med Mol Imaging. 2020 Jan 3. doi: 10.1007/s00259-019-04671-3. [Epub ahead of print] PubMed PMID: 31901102.
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