3. Treatment for a PROS disorder may involve targeted options, surgical interventions, and supportive care.
Historically, treatment for overgrowth syndromes such as PROS primarily involved conservative management, focusing on addressing complications through surgical excision, orthopedic surgery, sclerotherapy, embolization, and compressive therapies. However, these strategies often proved insufficient, and patients frequently experienced relapse and progression of the condition. Indeed, PROS is a complex condition that requires a multifaceted treatment approach.
The discovery of the PIK3/AKT/mTOR activation pathway in these syndromes marked a significant therapeutic breakthrough. Targeted therapies, such as the use of mTOR inhibitors like sirolimus, have shown benefits in treating venous and lymphatic malformations in patients with PROS. More recently, a selective PIK3CA inhibitor, alpelisib, has been approved. This drug has demonstrated remarkable improvements in patients with various PROS phenotypes, including reductions in capillary malformations; cessation of chronic gastrointestinal bleeding; and improvements in scoliosis and cognitive function, particularly in patients with MCAP syndrome.
Supportive care is also a critical component of managing PROS. This includes surgical interventions for significant overgrowth, orthopedic care for scoliosis and leg-length discrepancies, and neurosurgical interventions for neurologic complications such as obstructive hydrocephalus and epilepsy. Vascular and lymphatic malformations may be treated with sclerotherapy, laser therapy, or medications such as sirolimus. Additionally, routine treatment for associated conditions such as cardiac and renal abnormalities, intellectual disabilities, polydactyly, coagulopathy, and hypothyroidism is essential. For those with pain, identifying and treating the underlying cause is crucial. In cases of severe persistent hypoglycemia, ongoing treatment, which may include cornstarch administration, is necessary. Owing to the complexity and varied manifestations of PROS, specialized multidisciplinary care for diagnosis, follow-up, and optimal management is recommended.
4. PROS is a heterogeneous condition, and the clinical presentation can vary widely among affected individuals.
PROS is a complex and heterogeneous condition characterized by a wide range of clinical presentations, reflecting the diversity of affected tissues and the extent of overgrowth. Phenotypes within PROS are diverse and can range from a single lesion (ie, solitary macrodactyly) to systemic diseases (ie, Klippel-Trenaunay syndrome and CLOVES syndrome).
This heterogeneity is primarily due to the timing of the onset of the somatic causative PIK3CA pathogenic variants during embryonic and fetal development, influencing the degree of mosaicism and the combination of tissues involved (eg, neural progenitor cell pathogenic variants can lead to postnatal megalencephaly and hydrocephalus). Moreover, different gain-of-function variants in PIK3CA lead to varying levels of hyperactivation of the PI3K/AKT/mTOR pathway, resulting in diverse severity of abnormal proliferation of mesodermal and ectodermal tissues from embryogenesis onward.
This spectrum of symptoms underscores the complexity and variability of PROS, necessitating a tailored approach to diagnosis and management.
5. Regular surveillance is crucial for the effective management of PROS
Comprehensive and regular monitoring is essential to address the diverse and evolving clinical manifestations of PROS. During each medical visit, it is essential to measure growth parameters, including head circumference and the length of arms, hands, legs, and feet. This assessment helps identify any new neurologic symptoms such as seizures, changes in muscle tone, or signs of Chiari malformation.
Additionally, monitoring the patient’s developmental progress, behavior, and motor skills is vital. Clinical assessments for conditions like scoliosis and abdominal examinations for organomegaly or abdominal masses are also recommended.
Imaging plays a significant role in the ongoing evaluation of PROS. Serial head MRI is advised, with the frequency depending on the initial severity of findings and the degree of brain maturation. For patients with central nervous system overgrowth or dysplasia, brain MRI every 6 months until age 2 years, followed by annual scans until age 8 years, is recommended to monitor for progressive hydrocephalus and Chiari malformation.
Further specialized assessments may be required based on individual clinical indications. These include monitoring of vascular and lymphatic malformations, radiographs of limbs in cases of limb overgrowth, and follow-up ultrasonography or MRI for truncal overgrowth. Spinal MRI is necessary for patients with scoliosis or spinal deformities.
In cases of persistent hypoglycemia, particularly those needing ongoing treatment, blood glucose monitoring and evaluation of the hypothalamic-pituitary-adrenal axis are important.
Postsurgical patients, especially those with the CLOVES phenotype or vascular malformations, should have a hematology consultation to assess thrombosis and coagulopathy risks. The use of renal ultrasonography every 3 months until age 8 years is suggested for tumor screening, such as Wilms tumor, although this practice is somewhat controversial.
These comprehensive and tailored approaches are critical in managing the complex and varied aspects of PROS, ensuring optimal care and monitoring for affected individuals.
Dr. Keppler-Noreuil is professor of pediatrics, division of genetics and metabolism, University of Wisconsin School of Medicine and Public Health; clinical director, department of pediatrics, division of genetics and metabolism; program director, medical genetics and genomics residency, Waisman Center & UW Pediatric Specialty Clinics, University of Wisconsin. She has disclosed no relevant financial relationships.
A version of this article appeared on Medscape.com.