Case Study: A 3.5-Year-Old Male with a Persistent, Itchy Subcutaneous Thigh Nodule

Case at a Glance

A 3.5-year-old boy presented with a four-month history of an itchy, non-painful, palpable subcutaneous nodule on his left thigh. Serial ultrasounds showed a growing, vascular soft tissue lesion with an uncertain etiology, prompting discussion regarding the next steps in diagnosis, including MRI versus excisional biopsy.

Patient's Story

The patient is a healthy 3.5-year-old male with no significant past medical history, presenting with a parental complaint of a lump on his son's lower left thigh. The lesion was first noticed approximately four months prior to the initial consultation. The parents report the lump is not visible to the naked eye but is easily palpable. A key feature is pruritus (itchiness) at the site, which the child frequently scratches; the lump becomes more prominent after scratching. The lesion is reportedly non-painful and non-tender to palpation. The parents expressed significant anxiety regarding the possibility of a malignancy, such as a soft tissue sarcoma or lymphoma, particularly given the persistent nature of the lesion.

Initial Assessment

On physical examination, the patient was well-appearing and in no distress. Examination of the lower left anterior thigh revealed a palpable, firm, subcutaneous nodule. The nodule felt relatively immobile, and the overlying skin was normal in appearance with no discoloration or temperature change. The patient did not exhibit any pain response upon palpation. No other lymphadenopathy or masses were noted. The remainder of the physical exam was unremarkable.

The Diagnostic Journey

An initial diagnostic workup was initiated to characterize the lesion.

An X-ray of the left femur was performed, which showed skeletally immature bone with no evidence of suspicious bony lesions or cortical disruption.

A targeted soft tissue ultrasound was performed. The initial report described a hypoechoic mass located approximately 3 mm deep to the skin surface, within the soft tissues. It measured 7 x 4 x 12 mm and demonstrated internal vascularity and some echogenic regions. The radiologist concluded that the lesion was a solid, vascular mass of indeterminate origin, noting it was not typical for a lymph node and did not appear to involve the bone.

Three weeks later, a follow-up ultrasound was conducted to assess for any changes. The lesion was again identified in the subcutaneous tissues of the left anterior thigh. It now measured 13 x 8 x 5 mm, indicating a slight interval increase in size. The appearance was described as a heterogeneous, hypoechoic lesion with an internal echogenic area and vascularity. The impression noted a nonspecific vascular soft tissue lesion, with a differential diagnosis including a reactive lymph node or an angioleiomyoma. A follow-up ultrasound in three months was recommended.

The family and clinical team noted the conflicting reports regarding the likelihood of a lymph node and the documented growth of the lesion.

Final Diagnosis

A definitive diagnosis remains pending. The differential diagnosis based on imaging includes a benign entity such as a reactive lymph node or angioleiomyoma. However, given the lesion's persistence, growth, and atypical features (itchiness without pain, which is less common for angioleiomyoma), a low-grade soft tissue malignancy cannot be entirely excluded without tissue sampling.

Treatment Plan

The recommended next step from the radiology department was an MRI to better characterize the soft tissue lesion. However, significant logistical challenges were identified, including a wait time of over four months for the procedure and the requirement for sedation or general anesthesia in a child of this age, which carries its own risks and potential for motion artifact.

An alternative management strategy was discussed: proceeding directly to an excisional biopsy. This approach would provide a definitive histopathological diagnosis while also being therapeutic. Given the lengthy wait for an MRI and the anxiety surrounding the uncertain diagnosis, surgical excision was considered a viable and potentially more efficient option.

Outcome and Follow-up

The case is ongoing. The patient and his family are currently weighing the options of waiting for a sedated MRI versus proceeding with an excisional biopsy for diagnosis and treatment. The primary goal is to obtain a definitive diagnosis to guide any further management and to alleviate parental anxiety.