Ubiquitous expression of Akt1 p.(E17K) results in vascular defects and embryonic lethality in mice.

Proteus syndrome is a progressive overgrowth disorder with vascular malformations caused by mosaic expression of the AKT1 c.49G > A, p.(E17K) activating variant which was predicted to cause lethality if expressed ubiquitously. To test that hypothesis, we used the ACTB-Cre gene to activate a conditional Akt1 p.(E17K) allele in the mouse. No offspring that was heterozygous for both Cre and the conditional allele (ßA-Akt1WT/flx) was viable. Fewer than expected numbers of ßA-Akt1WT/flx embryos were seen beginning at E11.5, but a few survived until E17.5. The phenotype ranged from mild to severe, but generally ßA-Akt1WT/flx embryos had fewer visible blood vessels and more hemorrhages than their wild-type littermates, which was suggestive of a vascular abnormality. Examination of E13.5 limb skin showed a primitive capillary network with increased branching complexity and abnormal patterning compared with wild-type skin. By E15.5, wild-type skin had undergone angiogenesis and formed a hierarchical network of remodeled vessels, whereas in ßA-Akt1WT/flx embryos, the capillary network failed to remodel. Mural cell coverage of the blood vessels was also reduced in ßA-Akt1WT/flx skin compared with that of wild type. Restricting expression of Akt1E17K to endothelial, cardiac or smooth muscle cells resulted in viable offspring and remodeled vasculature and did not recapitulate the ßA-Akt1WT/flx phenotype. We conclude that ubiquitous expression of Akt1E17K suppresses remodeling and inhibits the formation of a normal skin vasculature. We postulate that this failure prevents proper circulation necessary to support the growing embryo and that it is the result of interactions of multiple cell types with increased AKT signaling.

Clinical report: one year of treatment of Proteus syndrome with miransertib (ARQ 092).

A 20-yr-old man with Proteus syndrome (PS) and somatic mosaicism of the AKT1 c.49G > A p.(E17K) variant had asymmetric overgrowth of the right frontal and facial bones, asymmetric spinal overgrowth with thoracolumbar scoliosis, dilatation of the inferior vena cava, testicular cystadenoma, bilateral knee deformities, macrodactyly, and apparent intellectual disability. Miransertib (ARQ 092) is an oral, allosteric, selective pan-AKT inhibitor initially developed for cancer therapeutics, now being evaluated for the treatment of PS. After baseline evaluation, the patient started unblinded treatment of 10 mg oral miransertib daily (∼5 mg/m2/day), escalated to 30 mg daily (∼15 mg/m2/day), and then to 50 mg daily (∼25 mg/m2/day) after 3 mo of treatment. Adverse events included dry mouth, one episode of gingivostomatitis, and loose, painful dentition due to preexisting periodontal disease, all of which resolved spontaneously. After 11 mo of treatment, the patient reported improved general well-being, increased mobility of the ankle, spine, and hands, a subjective decrease in size of the right facial bone overgrowth, and reduced areas of cerebriform connective tissue nevi on the soles. Whole-body MRI findings were stable without apparent disease progression. We conclude that 1 yr of treatment with miransertib was beneficial in this case.

Redundant plantar skin folds.

A 46-year-old female patient presented with photosensitivity, symmetric arthritis, episodic plantar pain and strikingly redundant plantar skin folds, likely due to lipoatrophy after recurrent episodes of plantar panniculitis. In this context, leukopenia with lymphopenia, thrombocytopenia and positive antinuclear antibodies were revelatory for systemic lupus erythematosus. However, a small cerebriform plantar collagenoma, along with discrete dysmorphic features with downslanting palpebral fissures and mild right ptosis, second and third syndactyly and a larger first right toe since childhood, and early-onset bilateral ovarian cystadenoma, suggested a minimal Proteus syndrome. Genetic confirmation could not be performed. As adipose tissue dysregulation may be a feature of Proteus syndrome, the possible mechanisms leading to localized lipoatrophy in this setting are discussed. This case enlights intriguing links between adipogenesis, inflammation and dysmorphology. From a practical point of view, finding and treating an over-imposed inflammation could help limit damage in a hamartomatous syndrome.

Histopathological features of Proteus syndrome.

BACKGROUND: Proteus syndrome is a rare, sporadic overgrowth disorder for which the underlying genetic defect remains unknown. Although the clinical course is well-described there is no systematic histopathological description of the lesional pathology. OBJECTIVE: To describe the histopathological features encountered in a series of patients with Proteus syndrome from a single centre. METHODS: Patients with Proteus syndrome who had undergone therapeutic surgical resection or biopsy were identified from a database and the histopathological findings were reviewed, with particular regard to descriptive features of the underlying tissue abnormality. RESULTS: There were 18 surgical specimens from nine patients, median age 4 years (range 1-9), classified into four main categories: soft-tissue swellings (lipomatous lesions), vascular anomalies (vascular malformation and haemangioma), macrodactyly (hamartomatous overgrowth) and others (sebaceous naevus and nonspecific features). In all cases, the clinical features of overgrowth were due to increased amounts of disorganized tissue, indicating a hamartomatous-type defect in which normal tissue constituents were present, but with an abnormal distribution and architecture. Vascular malformations represented a prominent category of lesions, accounting for 50% of the specimens, predominantly comprising lymphatic and lymphovascular malformations. No malignancy or cytological atypia was identified in any case. CONCLUSIONS: The histopathological features of lesions resected from children with Proteus syndrome predominantly include hamartomatous mixed connective tissue lesions, benign neoplasms such as lipomata, and lymphatic-rich vascular malformations.

Proteus syndrome: a natural clinical course of Proteus syndrome.

A 16-year-old Korean male patient presented with macrodactyly, hemihypertrophy of the face and extremities, plantar cerebriform hyperplasia, a subcutaneous mass of the left chest, macrocephaly and verrucous epidermal nevi. These findings are consistent with Proteus Syndrome. The clinical features, etiology, management, natural course and differential diagnosis of this case are discussed.

Proteus syndrome: a case report.

Proteus syndrome is a rare genetic disorder, characterized by partial gigantism of the hands and/or feet, asymmetry of the limbs, plantar hyperplasia, multiple hamartomatous subcutaneous tumors, hyperostoses, and long bone overgrowth. A one day old Thai male infant is reported with macrosomia, hemihypertrophy of the left side of the face and left leg, large feet, macrodactyly of toes, plantar hyperplasia, large subcutaneous mass with a violet-red surface over the left side of the chest wall and a large port-wine stain involving the lateral aspect of the right chest wall. The clinical findings, diagnostic criteria, differential diagnosis, and management of the Proteus syndrome are reviewed.

The multifaceted challenges of Proteus syndrome.

Proteus syndrome is a rare and sporadic disorder that causes postnatal overgrowth of multiple tissues in a mosaic pattern. The overgrowth can involve skin, subcutaneous tissue, connective tissue (including bone), the central nervous system, and viscera. Complications of Proteus syndrome include, among others, progressive skeletal deformities, invasive lipomas, benign and malignant tumors, and deep venous thrombosis with pulmonary embolism. Care of patients with Proteus syndrome presents significant challenges to both physicians and parents because of the various medical as well as psychosocial consequences of the disease. Herein, the case of a 5-year-old patient who manifested a number of these complications is presented. Current knowledge about the diagnosis, natural history, etiology, and management of the disorder is reviewed.