Israel Medical Association Journal

Neck masses are a common yet challenging presentation in pediatric patients. They may be caused by congenital, inflammatory, neoplastic, or vascular issues. The diverse nature of these masses can make definitive diagnosis difficult for clinicians. Several classification systems exist to categorize neck masses, considering factors such as age at presentation, anatomical location, imaging characteristics, and underlying etiology [1].

These masses often reflect benign infectious, inflammatory, or congenital etiologies. However, in certain cases, lymphadenopathy or other neck masses may indicate an underlying malignancy, thereby serving as a significant source of anxiety for patients and their families.

Fibromatosis colli (FMC) is characterized by a diffuse enlargement of the sternocleidomastoid muscle (SCM), usually in infancy. FMC, initially described as SCM tumors in childhood, is detected in 0.4% of live births but is among the most frequent perinatal neck masses [2].

Gross hematuria is uncommon in the neonatal period, with an estimated incidence of 0.21 per 1000 admissions in infants younger than one month. Although renal vein thrombosis is the most common cause, various etiologies, including congenital anomalies, must be considered. Anterior urethral valve (AUV) is a rare congenital anomaly that can cause severe obstruction and significantly impact the proximal urinary system [1].

Anatomically, AUV can cause obstruction of varying severity depending on the size and configuration of the valve [2]. The pathophysiology of AUV involves abnormal development of the urethral folds in the anterior urethra, typically at the penoscrotal junction, bulbar urethra, or penile urethra. These valves form cusp-like structures that allow antegrade flow of urine but obstruct during voiding, leading to progressive dilatation of the proximal urethra and upstream urinary tract [3].

Recent data from a matched cohort study at a high-risk pediatric center found that AUV patients demonstrate significantly lower creatinine levels at initial presentation and potentially better renal outcomes compared to posterior urethral valve (PUV) patients [4]. Prenatal diagnosis of anterior urethral anomalies is feasible as early as the second trimester, with characteristic findings including anterior urethral dilation and a keyhole sign on prenatal ultrasound [5]. Unlike PUV, which are more commonly reported, AUV presenting with gross hematuria in the neonatal period is exceptionally rare, making this case particularly noteworthy for clinicians.