Heterotopic squamous epithelial inclusion cyst in a cervical lymph node in a child: a case report and literature review.

Background: A squamous epithelial inclusion cyst in a lymph node is a rare heterotopic phenomenon. Heterotopic squamous inclusion cysts in cervical lymph nodes are even rarer, and to date, only 3 such cases have been reported in the literature, none of which have described the ultrasound features. Here, we report a pediatric case, focusing on the ultrasonographic manifestations of the disease and the differential diagnosis of cervical space-occupying lesions in children. Case Description: We report the case of a 6-year-old boy in good health, who presented with a non-tender mass on the right side of the neck 1 month earlier. Some 7 days before admission, the mass gradually increased in size and became tender. Laboratory tests showed an increase in C-reactive protein of 17 mg/L (normal range: 0-8 mg/L). The physical examination revealed a palpable 3.0 cm × 2.0 cm mass with tenderness and poor mobility in the right submandibular region. Doppler ultrasonography showed an oval, ill-defined mass in the right submandibular area, consisting of a peripheral homogeneous hypoechoic component with hilar-like vascularity and an internal heterogeneous very hypoechoic component with patchy hyperechoic areas. The computed tomography (CT) scan showed a heterogeneously hypodense mass with irregular annular enhancement in the right submandibular region. Lymph node tuberculosis or space-occupying lesions were suspected based on the clinical and imaging findings. The mass was completely excised by surgery. The pathological diagnosis was a secondary infection of squamous epithelial inclusion cysts in the right cervical lymph node. The peripheral homogeneous hypoechoic component was normal lymph node tissue, and the internal heterogeneous very hypoechoic component was a squamous inclusion cyst with keratin debris. The patient was followed up for a total of 3 times after surgery, and no recurrence of the tumor was found. Conclusions: Ultrasonography can help in the early diagnosis of heterotopic squamous inclusion cysts in children's cervical lymph nodes, and can be used to differentiate other cervical lesions. We reviewed the literature and found that this heterotopic phenomenon was more likely to occur in the submandibular region of the neck in younger patients. Surgery may be an effective treatment for this disease.