First webspace Morton's neuroma case report with literature review.

Morton's neuromas are benign lesions of the inter-digital nerves within the foot. They are most commonly found in the second and third webspace. Morton's neuroma of the first webspace is very rare. A case of a 42-year-old female who presented complaining of long standing forefoot pain is presented. The patient was diagnosed with a soft tissue tumor in the 1st webspace. An excisional biopsy of the tumour confirmed a Morton's neuroma. Very few cases of Morton's neuroma in the first webspace have been reported in the literature.

Functional and patient reported outcomes following lateral hallucal sesamoidectomy.

BACKGROUND: Lateral hallucal sesamoidectomy is an infrequently performed procedure indicated for patients with sesamoid pathology failing conservative treatment. Concerns exists regarding patient satisfaction, plantar scar pain, hallux malalignment and metatarsophalangeal joint (MTPJ) movement restriction following sesamoidectomy. This study aims to assess patient satisfaction after lateral hallucal sesamoidectomy via the plantar approach. METHODS: In this retropective study with prospective follow-up, all patients who underwent lateral hallucal sesamoidectomy between January 2004 and December 2017 were reviewed. Twelve patients (14ft.) were available for final assessment. Outcome measures were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) clinical rating scale and the Self-Reported Foot and Ankle questionnaire (SEFAS). Patients were assessed clinically and radiologically. The average postoperative follow-up was 111.5 months (range 28-177 months). RESULTS: All patients reported excellent outcome scores with a mean SEFAS score of 46.08 (range 43-48) and a mean AOFAS score of 92.33 (range 78-100) at final follow-up. All twelve patients reported their outcome as being excellent. No malalignment was noted clinically, however, three patients had a noticeable increase in the gap between the hallux and second toe when compared to the contralateral side. Range of motion at the MTPJ was preserved with a mean dorsiflexion of 80.83° (range 70-90°) and a mean plantarflexion was 25.83° (range 0-30°). None of the patients experienced any pain, discomfort or irritation related to the plantar scar. One patient developed neuroma like symptoms in the first web space. CONCLUSION: Lateral hallucal sesamoidectomy via a plantar approach is an effective and reliable treatment option as demonstrated by the high levels of patient satisfaction, preservation of function, excellent PROM scores and limited complications in this study. LEVEL OF EVIDENCE: Level 4.

The benefit of pharmacological venous thromboprophylaxis in foot and ankle surgery.

BACKGROUND: Ten percent of patients with a deep-vein thrombosis (DVT) will develop a fatal pulmonary embolism (PE), often initially asymptomatic. The risks and benefits of pharmacological thromboprophylaxis are well documented in respect of total joint arthroplasty and hip fractures, but little is understood about the incidence of venous thromboembolism (VTE) or the potential risks and benefits of chemoprophylaxis in foot and ankle surgery. OBJECTIVE: To determine whether prophylactic chemoprophylaxis had any impact on the prevention of VTE in a cohort of foot and ankle surgical patients requiring the combination of below-knee cast immobilisation and non-weightbearing for ≥4 weeks. METHODS: Between March 2014 and April 2015, a prospective cohort study of 142 patients was performed. All completed a thrombosis risk assessment form prior to surgery and were commenced on rivaroxaban (Xarelto) 10 mg/d postoperatively. The primary outcome measure was clinical VTE confirmed by compression ultrasonography (DVT) or a ventilation/perfusion scan (PE). RESULTS: Three patients (2.1%) developed a clinical DVT. Two did so well beyond the immobilisation and anticoagulation period, and one was non-compliant with therapy. The average risk factor score in this subgroup was 7. No patient had a DVT while on the prescribed regimen of anticoagulant therapy. Five patients (3.5%) developed wound breakdown, two requiring surgical debridement with local skin flap closure. One case of menorrhagia that may have been linked to the anticoagulant therapy was reported. When compared with a previous study, pharmacological thromboprophylaxis significantly reduced VTE risk (p=0.02). CONCLUSIONS: Oral pharmacological thromboprophylaxis significantly reduces the risk of VTE in patients requiring cast immobilisation and non-weightbearing following foot and ankle surgery. The risk/benefit ratio favours this treatment as opposed to the treatment of major morbidity following non-fatal VTE.

Correlation between rivaroxaban (Xarelto) plasma activity, patient clinical variables and outcomes in a South African centre.

BACKGROUND: Low-molecular-weight heparin and vitamin K antagonists such as warfarin are the gold standard for prohylaxis and treatment of venous thromboembolic disease (VTED). Direct oral anticoagulants (DOACs) result in predictable anticoagulation with significantly reduced inter- and intra-patient variability. DOAC absorption is rapid, with a short half-life and relatively few drug interactions. DOACs are effective and safe at fixed doses without activity monitoring. However, specific situations may require assessment of accurate drug activity. Rivaroxaban, a DOAC targeting activated coagulation factor X (FXa), is registered for the prevention and treatment of VTED in South Africa. OBJECTIVES: To establish a prophylactic rivaroxaban activity level range and determine any associations with clinical complications, viz. haemorrhage and/or thrombosis. METHODS: Samples from 115 orthopaedic patients were tested 3 hours after a prophylactic oral dose of 10 mg rivaroxaban with STAGO rivaroxaban anti-FXa reagent on an automated coagulation analyser. Patient demographics and clinical outcomes were documented. RESULTS: The mean rivaroxaban anti-FXa level was 105.7 ng/mL. Two patients developed adverse events on therapy. One patient had minor bleeding (menorrhagia) (drug activity level 288.7 ng/mL) and another a deep-vein thrombosis (drug activity level 34.7 ng/mL). Statistical analysis demonstrated an association between drug activity and advancing age (p=0.008), most apparent among those aged ≥65 years. CONCLUSIONS: Measuring rivaroxaban activity levels reduces uncertainty if treatment failure and complications occur. Patients aged ≥65 years should be closely monitored. A local rivaroxaban activity level for patients on rivaroxaban prophylaxis has been established.

Efficacy of CHK inhibitors as single agents in MYC-driven lymphoma cells.

CHK1 and CHK2 function as effectors of cell cycle checkpoint arrest following DNA damage. Small molecule inhibitors of CHK proteins are under clinical evaluation in combination with chemotherapeutic agents known to induce DNA damage. We examined whether CHK inhibitors could be effective as single agents in malignant cells with inherent DNA damage because of deregulated expression of the oncogene c-Myc. Eµ-myc lymphoma cells showed a dramatic increase in the extent of DNA damage and DNA damage response (DDR) signalling within 1 h of treatment with CHK1 inhibitors followed by caspase-dependent apoptosis and cell death. In p53 wild-type/ARF null Eµ-myc lymphoma cells, apoptotic cell death was preceded by accumulation of DNA damage and the amount of DNA damage correlated with the extent of cell death. This effect was not observed in normal B cells indicating that DNA damage accumulation following CHK inhibition was specific to Eµ-myc lymphoma cells that exhibit inherent DNA damage because of MYC-induced replication stress. Similar results were obtained with another structurally distinct CHK-inhibitor. Eµ-myc p53 null lymphoma cells were more sensitive to a dual CHK1/CHK2 inhibitor than to a CHK1-specific inhibitor. In all cases, the level of DNA damage following treatment was the most consistent indicator of drug sensitivity. Our results suggest that CHK inhibitors would be beneficial therapeutic agents in MYC-driven cancers. We propose that inhibitors of CHK can act in a synthetically lethal manner in cancers with replication stress as a result of these cancers being reliant on CHK proteins for an effective DDR and cell survival.

Association of paediatric mastocytosis with a polymorphism resulting in an amino acid substitution (M541L) in the transmembrane domain of c-KIT.

BACKGROUND: The receptor tyrosine kinase c-KIT plays a key role in normal mast cell development. Point mutations in c-KIT have been associated with sporadic or familial mastocytosis. OBJECTIVES: Two unrelated pairs of apparently identical twins affected by cutaneous mastocytosis attending the Mastocytosis Clinic at the Royal Children's Hospital, Melbourne, provided an opportunity to assess the possible contribution of c-KIT germline mutations or polymorphisms in this disease. METHODS: Tissue biopsy, blood and/or buccal swab specimens were collected from 10 children with mastocytosis. To detect germline mutations/polymorphisms in c-KIT, we studied all coding exons by denaturing high pressure liquid chromatography. Exons showing mismatches were examined by direct sequencing. The influence of the substitution identified was further examined by expressing the variant form of c-KIT in factor-dependent FDC-P1 cells. RESULTS: In both pairs of twins, a heterozygous ATG to CTG transition in codon 541 was observed, resulting in the substitution of a methionine residue in the transmembrane domain by leucine (M541L). In each case, one parent was also heterozygous for this allele. Expression of M541L KIT in FDC-P1 cells enabled them to grow in human KIT ligand (stem cell factor, SCF) but did not confer factor independence. Compared with cells expressing wild-type KIT at a similar level, M541L KIT-expressing cells displayed enhanced growth at low levels of SCF, and heightened sensitivity to the KIT inhibitor, imatinib mesylate. CONCLUSIONS: The data suggest that the single nucleotide polymorphism resulting in the substitution M541L may predispose to paediatric mastocytosis.

Phosphatidylinositol 3 kinase contributes to the transformation of hematopoietic cells by the D816V c-Kit mutant.

Stem cell factor (SCF) binds the receptor tyrosine kinase c-Kit and is critical for normal hematopoiesis. Substitution of valine for aspartic acid 816 (D816V) constitutively actives human c-Kit, and this mutation is found in patients with mastocytosis, leukemia, and germ cell tumors. Immortalized murine progenitor cells (MIHCs) transduced with wild-type c-Kit proliferate in response to SCF, whereas cells expressing D816V c-Kit (MIHC-D816V) are factor-independent and tumorigenic. However, the mechanisms mediating transformation by D816V c-Kit are unknown. The objective of this study was to identify signaling components that contribute to D816V c-Kit-mediated transformation. SCF stimulates association of p85PI3K with phosphorylated tyrosine 721 of wild-type c-Kit. Phosphatidylinositol 3 kinase (PI3K) subsequently contributes to the activation of Akt and Jnks. In contrast, these studies demonstrated that the D816V c-Kit mutant was constitutively associated with phosphorylated p85PI3K, and, downstream of PI3K, Jnk 1 and Jnk 2 were activated but Akt was not. Interestingly, Erks 1 and 2 were not constitutively activated by D816V c-Kit. Thus, D816V c-Kit maintains the activity of PI3K but not of all signaling pathways activated by wild-type c-Kit. Further, all pathways downstream of PI3K are not constitutively active in MIHC-D816V cells. Studies with a PI3K inhibitor and D816V/Y721F c-Kit, a mutant incapable of recruiting PI3K, indicate that constitutive activation of PI3K through direct recruitment by D816V c-Kit plays a role in factor-independent growth of MIHC and is critical for tumorigenicity.

Intracellular P-gp contributes to functional drug efflux and resistance in acute myeloid leukaemia.

Drug compartmentalization as well as drug efflux can contribute to drug resistance. We demonstrate the presence of P-gp in intracellular vesicles in certain AML cell lines and show localization of DNR to a similar subcellular compartment(s) that can be altered in the presence of P-gp inhibitors. Analysis of leukaemic cell lines and 50 AML patient samples showed that the level of P-gp mRNA or total P-gp protein correlated better with drug efflux than surface P-gp protein, suggesting that intracellular P-gp may contribute to MDR in AML. Therefore, the level of total P-gp protein or mRNA may be a better indicator of MDR than surface P-gp protein. In addition, we provide evidence for a novel mechanism of drug sequestration in K562 myeloid leukaemic cells.

Effects of mutant c-kit in early myeloid cells.

Activating mutations in c-Kit, the receptor for Stem Cell Factor (SCF), have been identified in dysplasias and leukaemias of the mast cell lineage and have been shown to contribute to transformation in model systems. Early myeloid cells also normally express c-Kit and their survival, proliferation and differentiation is promoted by SCF. It might therefore be expected that c-Kit mutations could also be involved in some acute and/or chronic myeloid leukaemias. We have found that mutant c-Kit (and normal c-Kit in the presence of SCF) provides a strong differentiation stimulus in normal and immortalised murine early myeloid cells. Since maturation of haemopoietic cells, with the exception of mast cells, results in down-regulation of c-Kit expression, the transforming effects of mutant receptor may be self-limiting in most lineages. This is consistent with the observation that multipotential progenitor cells from some patients with systemic mastocytosis express mutant c-Kit. However, c-Kit mutations have been observed in a few cases of myelodysplastic syndromes or AML without mast cell features. Oncogenesis involves multiple genetic changes and the phenotype of malignant haemopoietic cells expressing mutant c-Kit may be influenced by co-oncogenic events. For example mutations blocking the differentiative effect of mutant c-Kit might result in AML rather than mastocytosis. Thus the extent to which c-Kit mutations contribute to malignancies of early myeloid phenotype remains unknown, and resolution of this issue is complicated by the heterogeneity of this family of diseases.

Effects of mutant c-Kit in early myeloid cells.

Activating mutations in c-Kit, the receptor for Stem Cell Factor (SCF), have been identified in dysplasias and leukaemias of the mast cell lineage and have been shown to contribute to transformation in model systems. Early myeloid cells also normally express c-Kit and their survival, proliferation and differentiation is promoted by SCE It might therefore be expected that c-Kit mutations could also be involved in some acute and/or chronic myeloid leukaemias. We have found that mutant c-Kit (and normal c-Kit in the presence of SCF) provides a strong differentiation stimulus in normal and immortalised murine early myeloid cells. Since maturation of haemopoietic cells, with the exception of mast cells, results in down-regulation of c-Kit expression, the transforming effects of mutant receptor may be self-limiting in most lineages. This is consistent with the observation that multipotential progenitor cells from some patients with systemic mastocytosis express mutant c-Kit. However, c-Kit mutations have been observed in a few cases of myelodysplastic syndromes or AML without mast cell features. Oncogenesis involves multiple genetic changes and the phenotype of malignant haemopoietic cells expressing mutant c-Kit may be influenced by co-oncogenic events. For example mutations blocking the differentiative effect of mutant c-Kit might result in AML rather than mastocytosis. Thus the extent to which c-Kit mutations contribute to malignancies of early myeloid phenotype remains unknown, and resolution of this issue is complicated by the heterogeneity of this family of diseases.

Expression of constitutively activated human c-Kit in Myb transformed early myeloid cells leads to factor independence, histiocytic differentiation, and tumorigenicity.

The cDNAs encoding wild type (WT) human receptor tyrosine kinase c-Kit and a constitutively activated mutant, V816Kit, were introduced into granulocyte-macrophage colony-stimulating factor (GM-CSF )-dependent early murine hemopoietic cells, which had been transformed with activated Myb. WTKit cells were able to grow in the presence of the human ligand for Kit, stem cell factor (SCF ), but displayed reduced growth and clonogenic potential in either SCF or GM-CSF compared with the parental cells in GM-CSF. In contrast, V816Kit cells grew without factor at a higher rate than the parental cells in GM-CSF and displayed increased clonogenicity. Dissection of the growth characteristics in liquid culture showed that in the presence of appropriate factors, the different populations had similar proliferation rates, but that V816Kit profoundly increased cell survival compared with WTKit or parental cells. This suggests that the signals transduced by WTKit activated with SCF, and by V816Kit, were not identical. Also, WTKit and V816Kit-expressing cells both varied from the early myeloid progenitor phenotype of the parental cells and gave rise to a small number of large to giant adherent cells that expressed macrophage (alpha-naphthyl acetate) esterase and neutrophil (naphtol-AS-D-chloroacetate) esterase, were highly phagocytic and phenotypically resembled histiocytes. Thus, WTKit activated by SCF and V816Kit were able to induce differentiation in a proportion of Myb-transformed myeloid cells. The factor independent V816Kit cells, unlike the parental and WTKit expressing cells, were shown to produce tumors of highly mitotic, invasive cells at various stages of differentiation in syngeneic mice. These results imply that constitutively activated Kit can promote the development of differentiated myeloid tumors and that its oncogenic effects are not restricted to lineages (mast cell and B-cell acute lymphoblastic leukemia), which have been reported previously. Furthermore, the mixed populations of cells in culture and in the tumors phenotypically resembled the leukemic cells from patients with monocytic leukemia with histiocytic differentiation (acute myeloid leukemia-M5c), a newly proposed subtype of myeloid leukemia.

Enforced expression of full length c-Myb leads to density-dependent transformation of murine haemopoietic cells.

The oncogenic activation of c-myb has been associated with structural alterations to the Myb protein. Although such alterations can increase the ability of Myb to transform haemopoietic cells, it has been unresolved whether over-expression of wild type (WT) c-Myb can lead to transformation. We show here that infection with a retrovirus that expresses WT i.e. full length c-Myb leads to transformation of primary haemopoietic cells (as indicated by clonogenic assays). The transformed cells are similar to those obtained with carboxyl-truncated (CT) c-Myb in that they show phenotypic and morphological characteristics of early myeloid cells and remain dependent on exogenous growth factors. Cells expressing WTMyb form lower numbers of colonies on average and have a greater tendency to spontaneously differentiate than those expressing truncated c-Myb. Additionally, our results show that transformation by both forms of Myb is dependent on the density at which the infected cells are cultured, and that low levels of transformation can be increased by addition of conditioned medium from myb transformed cells grown at high density. This implies that transformation can be enhanced by the effects of an autocrine growth factor. Moreover, the production of, or sensitivity to, such a factor may be influenced by Myb itself, since CT Myb-infected cells cultured at low densities show higher levels of transformation than WT Myb-infected cells.