Low-Volume Metastases in Cervical Cancer: Does Size Matter?

The implementation of sentinel lymph node (SLN) biopsy is changing the scenario in the surgical treatment of early-stage cervical cancer, and the oncologic safety of replacing bilateral pelvic lymphadenectomy with SLN biopsy is currently under investigation. Part of the undisputed value of SLN biopsy is its diagnostic accuracy in detecting low-volume metastases (LVM) via pathologic ultrastaging. In early-stage cervical cancer, the reported incidence of LVM ranges from 4 to 20%. The prognostic impact and the role of adjuvant treatment in patients with LVM is still unclear. Some non-prespecified analyses in prospective studies showed no impact on the oncologic outcomes compared to node-negative disease. However, the heterogeneity of the studies, the differences in the disease stage and the use of adjuvant treatment, and the concomitant pelvic lymphadenectomy (PLND) make reaching any conclusions on this topic hard. Current guidelines suggest considering micrometastases (MIC) as a node-positive disease, while considering isolated tumor cells (ITC) as a node-negative disease with a low level of evidence. This review aims to highlight the unanswered questions about the definition, identification, and prognostic and therapeutic roles of LVM and to underline the present and future challenges we are facing. We hope that this review will guide further research, giving robust evidence on LVM and their impacts on clinical practice.

Outcome of patients with stage I immature teratoma after surveillance or adjuvant chemotherapy.

Objective: Immature teratomas are rare malignant ovarian germ cell tumours, typically diagnosed in young women, where fertility-sparing surgery is the treatment of choice. The role of adjuvant chemotherapy in stage I disease remains controversial. We evaluated the impact of surveillance versus chemotherapy on the recurrence rate in stage I immature teratomas. Methods: We collected a single centre retrospective series of patients with stage I immature teratomas treated with fertility-sparing surgery at San Gerardo Hospital, Monza, Italy, between 1980 and 2019. Potential risk factors for recurrence were investigated by multivariate logistic regression. Results: Of the 74 patients included, 12% (9/74) received chemotherapy, while 88% (65/74) underwent surveillance. Median follow-up was 188 months. No difference in recurrence was found in stage IA/IB and IC immature teratomas [10% (6/60) vs. 28.6% (4/14) (P=0.087)], grade 1, grade 2, and grade 3 [7.1% (2/28) vs. 14.3% (4/28) vs. 22.2% (4/18) (p=0.39)], and surveillance versus chemotherapy groups [13.9% (9/65) vs. 11.1% (1/9)) (p = 1.00)]. In univariate analysis, the postoperative approach had no impact on recurrence. The 5-year disease-free survival was 87% and 90% in the surveillance and chemotherapy groups, respectively; the overall survival was 100% in both cohorts. Conclusions: Our results support the feasibility of surveillance in stage I immature teratomas. Adjuvant chemotherapy may be reserved for relapses. However, the potential benefit of chemotherapy should be discussed, especially for high-risk tumours. Prospective series are warranted to confirm our findings. What is already known on this topic: To date, no consensus has been reached regarding the role of adjuvant chemotherapy in stage I immature teratomas of the ovary. Some studies suggest that only surveillance is an acceptable choice. However, guidelines are not conclusive on this topic. What this study adds: No difference in terms of recurrence was observed between the surveillance and the adjuvant chemotherapy group. All patients who relapsed were successfully cured with no disease-related deaths. How this study might affect research practice or policy: Adjuvant chemotherapy should be appropriately discussed with patients. However, it may be reserved for relapse according to our data.

Phase-Change Memory from Molecular Tellurides.

Phase-change memory (PCM) is an emerging memory technology based on the resistance contrast between the crystalline and amorphous states of a material. Further development and realization of PCM as a mainstream memory technology rely on innovative materials and inexpensive fabrication methods. Here, we propose a generalizable and scalable solution-processing approach to synthesize phase-change telluride inks in order to meet demands for high-throughput material screening, increased energy efficiency, and advanced device architectures. Bulk tellurides, such as Sb2Te3, GeTe, Sc2Te3, and TiTe2, are dissolved and purified to obtain inks of molecular metal telluride complexes. This allowed us to unlock a wide range of solution-processed ternary tellurides by the simple mixing of binary inks. We demonstrate accurate and quantitative composition control, including prototype materials (Ge-Sb-Te) and emerging rare-earth-metal telluride-doped materials (Sc-Sb-Te). Spin-coating and annealing convert ink formulations into high-quality, phase-pure telluride films with preferred orientation along the (00l) direction. Deposition engineering of liquid tellurides enables thickness-tunable films, infilling of nanoscale vias, and film preparation on flexible substrates. Finally, we demonstrate cyclable and non-volatile prototype memory devices, achieving performance indicators such as resistance contrast and low reset energy on par with state-of-the-art sputtered PCM layers.

Radical Hysterectomy in Early-Stage Cervical Cancer: Abandoning the One-Fits-All Concept.

Two pillars in modern oncology are treatment personalization and the reduction in treatment-related morbidity. For decades, the one-fits-all concept of radical hysterectomy has been the cornerstone of early-stage cervical cancer surgical treatment. However, no agreement exists about the prevalent method of parametrial invasion, and the literature is conflicting regarding the extent of parametrectomy needed to achieve adequate surgical radicality. Therefore, authors started investigating if less radical surgery was feasible and oncologically safe in these patients. Two historical randomized controlled trials (RCTs) compared classical radical hysterectomy (RH) to modified RH and simple hysterectomy. Less radical surgery showed a drastic reduction in morbidity without jeopardizing oncological outcomes. However, given the high frequency of adjuvant radiotherapy, the real impact of reduced radicality could not be estimated. Subsequently, several retrospective studies investigated the chance of tailoring parametrectomy according to the tumor's characteristics. Parametrial involvement was shown to be negligible in early-stage low-risk cervical cancer. An observational prospective study and a phase II exploratory RCT have recently confirmed the feasibility and safety of simple hysterectomy in this subgroup of patients. The preliminary results of a large prospective RCT comparing simple vs. radical surgery for early-stage low-risk cervical cancer show strong probability of giving a final answer on this topic.

Flux Growth, Crystal Structure, and Chemical Bonding of Yb2PdGe3, an AlB2 Superstructure within the Rare-Earth Series.

The complete structure revision of the RE2PdGe3 (RE = rare-earth metal) series revealed that Yb2PdGe3 is the only AlB2 ordered superstructure. Good-quality single crystals of this compound were successfully grown from molten indium flux, enabling accurate single-crystal investigations. Yb2PdGe3 crystallizes with the Ce2CoSi3-type structure in the hexagonal space group P6/mmm (no. 191) with lattice parameters a = 8.468(1) Å and c = 4.0747(7) Å. This structure is a four-order derivative of AlB2, composed of planar ∞2[PdGe3] honeycomb layers spaced by Yb species, located at the center of Ge6 and Ge4Pd2 hexagons. A superconducting transition is observed below the critical temperature of 4 K. A divalent state of Yb is deduced from magnetic susceptibility measurements below room temperature, which indicate an almost nonmagnetic behavior. A charge transfer from Yb to Pd and Ge was evidenced by the Quantum Theory of Atoms in Molecules (QTAIM) effective charges; polar four-atomic Ge-Pd/Yb and two-atomic Pd-Yb bonds were observed from the ELI-D (electron localizability indicator), partial ELI-D, and ELI-D/QTAIM intersections. The bonding interactions between Ge atoms within regular Ge6 hexagons are found to be intermediate between single bonds, as in elemental Ge, and higher-order bonds in the hypothetic Ge6H6 and Ge66- aromatic molecules.

Evaluation of family history in individuals with heterozygous BRCA pathogenic variants diagnosed with breast or ovarian cancer in a single center in Italy.

BACKGROUND: BRCA1 and BRCA2 gene mutations are responsible for 5% of breast cancer (BC) and 10-15% of ovarian cancer (EOC). The presence of a germline mutation and therefore the identification of subjects at high risk of developing cancer should ideally precede the onset of the disease, so that appropriate surveillance and risk-reducing treatments can be proposed. In this study, we revisited the family history (FH) of women who tested positive for BRCA mutations after being diagnosed with BC or EOC. METHODS: The National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology (NCCN Guidelines®), and the Italian Association of Medical Oncology (AIOM) guidelines were applied to the FH of 157 women who were referred to San Gerardo Hospital for genetic counseling. RESULTS: Almost 85% of women had an FH of BRCA-related cancer. 63.7% and 52.2% of women could have undergone genetic testing according to NCCN and AIOM testing criteria (p < .05) before tumor diagnosis. An FH of EOC was the most frequent NCCN criterion, followed by BC diagnosed <45 years old. Sixty-five percent of deceased women could have undergone genetic testing before developing cancer. CONCLUSIONS: FH is a powerful tool to identify high-risk individuals eligible for genetic counseling and testing. Testing of healthy individuals should be considered when an appropriately affected family member is unavailable for testing.

Use of staging for sex cord stromal tumours.

PURPOSE OF REVIEW: Sex cord-stromal tumours (SCSTs) are rare ovarian cancers. As in the literature, only small case series or case reports are published, gathering solid evidence about their management is challenging. Surgery plays a pivotal role, and accurate staging is one of the most important prognostic factors. This review focuses on the current evidence for surgical staging in the management of SCSTs. RECENT FINDINGS: Staging procedures have been inferred by epithelial ovarian cancers; however, they are often only partially performed, and most SCSTs therefore end up incompletely staged, raising the issue of the need for restaging or further treatments. In addition, some parts of the staging procedure have been questioned over the years, and lymphadenectomy is now considered unnecessary for SCSTs.The generally favourable prognosis of SCSTs, the introduction of minimally invasive surgery and fertility-sparing approaches is empowering the question of which staging procedures are beneficial for these patients. We reviewed the role of each staging procedure proposed by the guidelines in light of new scientific updates. SUMMARY: Surgical staging should always be performed. It includes peritoneal samplings (peritoneal washing, multiple peritoneal biopsies, omental biopsy and biopsy of any suspicious area), whereas lymphadenectomy could be omitted. Laparoscopy may be considered a feasible approach.

Neoadjuvant chemotherapy followed by radical surgery in locally advanced vulvar carcinoma: a single-institution experience.

BACKGROUND: Squamous cell carcinoma of the vulva is a rare malignancy that affects elderly women. About one-third of vulvar cancers are diagnosed in an advanced stage, requiring extensive surgery. Neoadjuvant chemotherapy (NACT) has been introduced to reduce local tumor burden. In this retrospective study, we analyze the efficacy and toxicity of NACT followed by radical surgery. METHODS: Patients with locally advanced vulvar cancer (LAVC) treated at our institution with neoadjuvant platinum and paclitaxel-based chemotherapy ± ifosfamide followed by surgery at our institution were retrospectively identified. RESULTS: Fourteen patients (93%) completed NACT with tolerable toxicities (G3-G4 toxicity: 30%). Thirteen patients (87%) underwent surgery. The overall clinical response rate on vulvar disease was 66% (20% complete response, 46% partial response), confirmed by histopathologic analysis, while on inguinal lymph nodes it was 69% (23% complete response, 46% partial response). At the pathologic examination, all patients had negative surgical margins. Three out of 9 patients (33%) with lesions infiltrating the urethral meatus and 4 patients out of 7 (57%) with anal involvement did not require urethral amputation or colostomy, respectively, after NACT. No severe postoperative complications were described. Overall survival at 5 years was 60%, and median overall survival was 76 months. CONCLUSION: NACT followed by surgery in locally advanced vulvar cancer is well tolerated and allows surgical modulation.

Tubal histopathological abnormalities in BRCA1/2 mutation carriers undergoing prophylactic salpingo-oophorectomy: a case-control study.

OBJECTIVE: To describe tubal histopathological abnormalities in women with germline BRCA1/2 mutations and in controls. METHODS: Consecutive women with BRCA1/2 mutations undergoing bilateral salpingo-oophorectomy between 2010 and 2020 in two centers (San Gerardo Hospital, Monza and San Matteo Hospital, Pavia) were considered in this analysis and compared with controls who had the same surgical procedure for benign conditions. Frequency of p53 signature, serous tubal intraepithelial carcinoma, and high-grade serous ovarian cancer were compared between the two groups. RESULTS: A total of 194 women with pathogenic BRCA1/2 mutations underwent prophylactic salpingo-oophorectomy. Of these, 138 women (71%) had a completely negative histological examination, while in 56 (29%) patients an ovarian or tubal alteration was reported. Among controls, 84% of patients had a p53wt signature, while 16% had a p53 signature. There was no difference in the frequency of a p53 signature between cases and controls; however, women with BRCA1/2 mutations were more likely to have pre-malignant or invasive alterations of tubal or ovarian epithelium (p=0.015). Among mutation carriers, older age both at genetic testing and at surgery was associated with an increased risk of having malignancies (OR=1.07, p=0.006 and OR=1.08, p=0.004, respectively). The risk of malignancy seems to be increased in patients with a familial history of high-grade serous ovarian cancer. Previous therapy with tamoxifen was significantly more frequent in patients with malignant lesions (40.0% vs 21.3%, p=0.006). CONCLUSION: We found that a p53 signature is a frequent finding both in BRCA1/2 mutation carriers and in controls, while pre-invasive and invasive lesions are more frequent in BRCA1/2 mutation carriers. Genetic and clinical characteristics are likely to affect the progression to malignancy.

Unpredicted but It Exists: Trigonal Sc2Ru with a Significant Metal-Metal Charge Transfer.

The Sc2Ru compound, obtained by high-temperature synthesis, was found to crystallize in a new trigonal hP45 structure type [space group P3̅m1; a = 9.3583(9) Å and c = 11.285(1) Å]: Ru@Sc8 cubes, Ru@Sc12 icosahedra, and uncommon Ru@Sc10 sphenocoronae are the building blocks of a unique motif tiling the whole crystal space. According to density functional theory studies, Sc2Ru is a metallic compound characterized by multicenter interactions: a significant charge transfer occurs from Sc to Ru, indicating an unexpectedly strong ionic character of the interactions between the two transition metals. Energy calculations support our experimental results in terms of stability of this compound, contributing to the recurrent discussion on the limits of the high-throughput first-principles calculations for metallic materials design.

La2Pd3Ge5 and Nd2Pd3Ge5 Compounds: Chemical Bonding and Physical Properties.

The two La2Pd3Ge5 and Nd2Pd3Ge5 compounds, crystallizing in the oI40-U2Co3Ge5 crystal structure, were targeted for analysis of their chemical bonding and physical properties. The compounds of interest were obtained by arc melting and characterized by differential thermal analysis, scanning electron microscopy, and X-ray diffraction both on powder and on a single crystal (for the La analogue), to ensure the high quality of the samples and accurate crystallographic data. Chemical bonding was studied by analyzing the electronic structure and effective QTAIM charges of La2Pd3Ge5. A significant charge transfer mainly occurs from La to Pd so that Ge species assume tiny negative charges. This result, together with the -(I)COHP analysis, suggests that, in addition to the expected homopolar Ge bonds within zigzag chains, heteropolar interactions between Ge and the surrounding La and Pd occur with multicenter character. Covalent La-Pd interactions increase the complexity of chemical bonding, which could not be adequately described by the simplified, formally obeyed, Zintl-Klemm scheme. Electric resistivity, specific heat, magnetization, and magnetic susceptibility as a function of temperature indicate for both compounds a metallic-like behavior. For Nd2Pd3Ge5, two low-temperature phase transitions are detected, leading to an antiferromagnetic ground state.

Polar-Covalent Bonding Beyond the Zintl Picture in Intermetallic Rare-Earth Germanides.

A comparative chemical bonding analysis for the germanides La2 MGe6 (M=Li, Mg, Al, Zn, Cu, Ag, Pd) and Y2 PdGe6 is presented, together with the crystal structure determination for M=Li, Mg, Cu, Ag. The studied compounds adopt the two closely related structure types oS72-Ce2 (Ga0.1 Ge0.9 )7 and mS36-La2 AlGe6 , containing zigzag chains and corrugated layers of Ge atoms bridged by M species, with La/Y atoms located in the biggest cavities. Chemical bonding was studied by means of the quantum chemical position-space techniques QTAIM (quantum theory of atoms in molecules), ELI-D (electron localizability indicator), and their basin intersections. The new penultimate shell correction (PSC0) method was introduced to adapt the ELI-D valence electron count to that expected from the periodic table of the elements. It plays a decisive role to balance the Ge-La polar-covalent interactions against the Ge-M ones. In spite of covalently bonded Ge partial structures formally obeying the Zintl electron count for M=Mg2+ , Zn2+ , all the compounds reveal noticeable deviations from the conceptual 8-N picture due to significant polar-covalent interactions of Ge with La and M ≠ Li, Mg atoms. For M=Li, Mg a formulation as a germanolanthanate M[La2 Ge6 ] is appropriate. Moreover, the relative Laplacian of ELI-D was discovered to reveal a chemically useful fine structure of the ELI-D distribution being related to polyatomic bonding features. With the aid of this new tool, a consistent picture of La/Y-M interactions for the title compounds was extracted.

A new glance on R2MGe6 (R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R2PdGe6 germanides.

The R2PdGe6 series (R = rare earth metal) was structurally characterized, and the results achieved were extended for a comprehensive study on R2MGe6 (M = another metal) compounds, employing symmetry-based structural rationalization and energy calculations. Directly synthesized R2PdGe6 exists for almost all R-components (R = Y, La-Nd, Sm and Gd-Lu) and even if with La is probably metastable. Several single crystal X-ray analyses (R = Y, Ce, Pr, Nd, Er and Lu) indicated oS72-Ce2(Ga0.1Ge0.9)7 as the correct structure. The alternative In-flux method, once optimized, produced three good quality R2PdGe6 single crystals: La2PdGe6 and Pr2PdGe6 turned out to be mS36-La2AlGe6-type non-merohedrally twinned crystals and Yb2PdGe6 is of oS72-Ce2(Ga0.1Ge0.9)7-type. The vacancy ordering phenomenon was considered as a possible cause of the symmetry reduction relations connecting the most frequently reported 2 : 1 : 6 structural models (oS18, oS72 and mS36) with the oS20-SmNiGe3 aristotype. The detected twin formation is consistent with the symmetry relations, which are discussed even considering the validity of the different structural models. DFT total energy calculations were performed for R2PdGe6 (R = Y and La) in the three abovementioned structural models, and for La2MGe6 (M = Pt, Cu, Ag and Au) in the oS18 and oS72 modifications. The results indicate that the oS18-Ce2CuGe6 structure, prevalently proposed in the literature, is associated with the highest energy and thus it is not likely to be realized in these series. The oS72 and mS36 polytypes are energetically equivalent, and small changes in the synthetic conditions could easily stabilize any of them, in agreement with experimental results obtained by direct and flux syntheses.

Yb9+xCuMg4-x (x = 0.034): A κ-Phase Formed by Lanthanoids.

Atom order in the crystal structures of Yb2Cu2-xMg (x = 0.17; Mo2FeB2-type; P4/mbm; a = 0.75592(2) nm; c = 0.40282(1) nm) and Yb9+xCuMg4-x (x = 0.034; Hf9Mo4B-type; P63/mmc; a = 1.0169(5) nm; c = 1.0290(5) nm) was determined from powder and X-ray single-crystal counter data analyses supported by electron probe microanalyses. Among the group of the so-called κ-phases, Yb9+xCuMg4-x is the first representative formed by a lanthanoid element. The structure of this κ-phase can be viewed as a typical network of corner-connected empty Yb6-octahedra, which encompass Yb6Mg6-icosahedra (filled by a mix of Mg/Yb atoms) and Yb6-trigonal prisms centered by Cu atoms to complete the three-dimensional metal framework. From another point of view, the same structure is considered as built from infinite polyicosahedral columns of Yb9Mg4 composition with Cu atoms located in trigonal prismatic interstices, highlighting similarities with other Yb-rich Yb-Cu-Mg phases. Density functional theory (DFT) calculations classify Yb9CuMg4 as a polar intermetallic. Metallic-like behavior is inferred from the Sommerfeld constant, γ = 49.2 mJ/mol·K(2), derived from the electronic density of states, calculated at the Fermi level. DFT integration of the f-density of states indicates almost completely filled f-states, revealing 13.6 and 13.7 electrons in the valence band for Yb1 and Yb2 atoms, respectively, close to the Yb(2+) ground state ((1)S0) for both Yb atoms. Magnetic susceptibility data recorded on the same compound are consistent with a nonmagnetic divalent Yb(2+) state. Temperature-dependent heat capacity data display a metallic behavior characterized by a small Sommerfeld constant γ = 64.8 mJ/mol·K(2) and a rather low Debye temperature ΘD = 140 K as typical for soft materials.

Vacancy ordering as a driving factor for structural changes in ternary germanides: the new R2Zn(1-x)Ge6 series of polar intermetallics (R = rare-earth metal).

Synthesis and structural characterization of the new compounds R2Zn1-xGe6 (R = La-Nd, Sm, Gd-Ho) is reported. A structural change was revealed along this series by careful analysis of single-crystal X-ray diffraction data. For light rare earths up to Tb the orthorhombic oS72-Ce2(Ga0.1Ge0.9)7 model was established; instead, the Dy compound represents a new structure type (P21/m, mP34, Z = 4, a = 7.9613(3) Å, b = 8.2480(4) Å, c = 10.5309(5) Å, ß = 100.861(1)°) being a superstructure of the mS36-La2AlGe6 prototype. The established structural models support the increase of Zn deficiency along the series, suggested by microprobe analysis, and its key role in governing structural changes. The vacancy ordering criterion was applied as a successful approach to find a general scheme including the structures of the ∼R2MGe6 compounds known up to now (R = rare-earth metal, M = transition metal, Mg, Al, Ga) and highlighting the subtle structural differences within this family. According to this scheme, these structures are obtained from a common aristotype (oS20-SmNiGe3) via symmetry reduction based on group-subgroup relations accompanied by ordering of vacancies. This approach was optimized with the help of the ToposPro software and extended to the R2Zn3Ge6 series, enriched with new members (R = Sm, Gd-Ho) during this work. Electronic structure calculations on La2ZnGe6 confirm the presence of infinite covalent germanium zigzag chains and three-bonded corrugated layers connected via Zn atoms to form a polyanionic network stabilized by La atoms.

New ternary germanides La4Mg5Ge6 and La4Mg7Ge6: crystal structure and chemical bonding.

The synthesis, structural characterization, and chemical-bonding peculiarities of the two new polar lanthanum-magnesium germanides La(4)Mg(5)Ge(6) and La(4)Mg(7)Ge(6) are reported. The crystal structures of these intermetallics were determined by single-crystal X-ray diffraction analysis. The La(4)Mg(5)Ge(6) phase crystallizes in the orthorhombic Gd(4)Zn(5)Ge(6) structure type [Cmc2(1), oS60, Z = 4, a = 4.5030(7) Å, b = 20.085(3) Å, c = 16.207(3) Å, wR2 = 0.0451, 1470 F(2) values, 93 variables]. The La(4)Mg(7)Ge(6) phase represents a new structure type with a monoclinic unit cell [C2/m, mS34, Z = 2, a = 16.878(3) Å, b = 4.4702(9) Å, c = 12.660(3) Å, ß = 122.25(3)°, wR2 = 0.0375, 1466 F(2) values, 54 variables]. Crystallographic analysis together with linear muffin-tin orbital band structure calculations reveals the presence of strongly bonded 3D polyanionic [Mg-Ge] networks balanced by positively charged La atoms in both stoichiometric compounds. The La(4)Mg(5)Ge(6) compound is related to Zintl phases, showing a prominent density of states pseudogap at the Fermi level. A distinctive feature of the La(4)Mg(5)Ge(6) structure is the presence of Ge-Ge covalent dumbbells; in La(4)Mg(7)Ge(6), the higher Mg content generates a polyanionic network consisting exclusively of Mg-Ge heterocontacts. Nevertheless, the frameworks of the two phases are structurally similar, as is highlighted in this work.

Anti-mackay polyicosahedral clusters in La-Ni-Mg ternary compounds: synthesis and crystal structure of the La(43)Ni(17)Mg(5) new intermetallic phase.

The crystal structure of the complex La(43)Ni(17)Mg(5) ternary phase was solved and refined from X-ray single crystal diffraction data. It is characterized by a very large unit cell and represents a new structure type: La(43)Ni(17)Mg(5) - orthorhombic, Cmcm, oS260, a = 10.1895(3), b = 17.6044(14), c = 42.170(3) A, Z = 4, wR1 = 0.0598, wR2 = 0.0897, 4157 F(2) values, 176 variables. The crystal structures of the La-rich La-Ni-Mg intermetallic phases La(4)NiMg, La(23)Ni(7)Mg(4), and La(43)Ni(17)Mg(5) have been comparatively analyzed. The constitutive fragments of these structures are binary polyicosahedral core-shell clusters of Mg(4)La(22) and Mg(5)La(24) compositions together with binary polytetrahedral clusters of nickel and lanthanum atoms. The structures of the Mg-La clusters are described in detail as a unique feature of the analyzed intermetallic phases; the dodecahedral Voronoi polyhedra are proposed as a useful tool to characterize polyicosahedral clusters. The arrangements of the building units in the studied phases show some regularities; particularly the i(4)3, i(5)3 and L-i(4) units, made up of polyicosahedral clusters and analogous to the Kreiner i(3) and L units, are proposed as structural blocks.