Non-surgical management of lingual lymphangioma: the sirolimus alternative

Lymphangiomas of the tongue, primarily microcystic (lymphangioma circumscriptum), pose a major therapeutic challenge in oral surgery. While surgical excision is classically considered, it often proves unfeasible without severe functional morbidity — such as partial glossectomy — and presents a high recurrence rate. This report documents the case of a six-year-old patient presenting with a right lingual mass extending to the floor of the mouth, responsible for episodes of acute dyspnoea and persistent pain, making surgical resection too risky.

The objective of this study is to evaluate the efficacy of sirolimus, an mTOR inhibitor, as a non-invasive medical alternative. This case is particularly notable as it constitutes the first report documenting the use of sirolimus monotherapy for an oral lymphangioma with minimal toxicity. The hypothesis tested is that the immunosuppressive and anti-proliferative action of the molecule can induce atrophy of the pathological lymphatic tissue. The evaluation of therapeutic success is based on clinical evolution and MRI data (T2), specifically measured after six months of treatment and six months after the end of therapy.

Methodological approach: a non-surgical alternative

This case report details the management of a lingual lymphangioma circumscriptum in a 6-year-old pediatric patient. The approach breaks with conventional invasive treatments by favoring drug monotherapy for a lesion deemed ineligible for complete surgical excision without major morbidity.

• Subject and Diagnosis: A young patient presenting with symptomatic macroglossia since the age of 2, with episodes of acute dyspnoea. The diagnosis was established by MRI imaging (T2 sequence) revealing a diffuse microcystic mass extending to the floor of the mouth, then validated by tissue biopsy.
• Therapeutic protocol: Oral administration of sirolimus at a dosage of 0.8 mg/m² every 12 hours. Outpatient follow-up aimed for a target residual blood concentration between 6 and 10 ng/mL.
• Safety measures: Due to the myelosuppressive effect of sirolimus, trimethoprim-sulfamethoxazole prophylaxis was prescribed to prevent the risk of Pneumocystis pneumonia.
• Evaluation of results: The treatment was maintained for nearly 17 months (started in December 2021). The efficacy analysis was based on clinical examination of functions (breathing, pain) and on a comparison of T2 MRI imaging performed at diagnosis, after 6 months of treatment, and 6 months after the end of the protocol.

Results: A complete clinical and radiological response under Sirolimus

Sirolimus treatment (monotherapy) was initiated in this six-year-old patient with an oral dosage of 0.8 mg/m² every 12 hours, targeting a trough level of 6 to 10 ng/mL. The results show rapid and sustained improvement, both functionally and structurally.

Qualitative observations and imaging

Magnetic resonance imaging (MRI) was the primary monitoring tool. Due to the high water content of lymphangiomas, T2 sequences allowed for precise visualization of regression kinetics:

• Volumetric reduction: Scans at 6 months of treatment, then at 6 months post-discontinuation, demonstrate a drastic reduction in hypertrophy of the right posterior part of the tongue.
• Lingual symmetry: Clinical photographs at 8 months post-treatment confirm a restoration of lingual symmetry and a reduction in the superficial nodular appearance.
• Tolerance: Despite the myelosuppressive profile of sirolimus, initial and follow-up laboratory tests remained unremarkable. Concomitant prophylaxis with trimethoprim-sulfamethoxazole prevented any opportunistic infectious complications.

Ultimately, the patient remained asymptomatic throughout the follow-up period, without any new episodes of respiratory distress or acute pain, validating the effectiveness of this non-surgical approach for a diffuse lymphatic malformation.

A credible medical alternative to major surgery

This case study illustrates a paradigm shift in the management of circumscribed lymphangiomas of the tongue. Traditionally, the treatment of these microcystic malformations relies on surgical excision, which is often debilitating, with a high risk of recurrence and functional morbidity (speech, swallowing). Here, the transition to sirolimus monotherapy made it possible to avoid a complex partial glossectomy in a six-year-old child.

Clinical results are significant: a disappearance of lingual pain within a few weeks and a visible reduction in the volume of the mass within a few months. T2-weighted MRI imaging confirmed the objective decrease of the lesion, thanks to the sensitivity of this examination to the water content of lymphangiomas. On a biological level, the efficacy of sirolimus — an mTOR inhibitor — is explained by its atrophying action on proliferating lymphatic tissue.

However, this study has inherent limitations due to its format (n=1). Although the toxicity profile is considered favorable, the management of side effects remains a critical point. Treatment-induced myelosuppression requires strict hematological monitoring and antibiotic prophylaxis against opportunistic infections, such as the concomitant use of trimethoprim-sulfamethoxazole observed here.

Compared to the data compiled by Wiegand (cited in the study), this case follows the trend of 80 to 90% partial responses observed with mTOR inhibitors for vascular malformations. This non-surgical approach offers a serious perspective for practitioners facing diffuse lesions where complete excision is deemed impossible or too risky.

Summary of results

This clinical case reports the efficacy of sirolimus, an mTOR inhibitor, as monotherapy for treating a lymphangioma circumscriptum of the tongue in a 6-year-old child. Administered at a dose of 0.8 mg/m² twice daily for 17 months, the treatment induced a major reduction in lesion volume and the disappearance of pain episodes and respiratory distress. The follow-up at more than 4 years confirms the long-term stability of the result without any clinical or radiological recurrence (T2 MRI).

In concrete terms, for the practitioner:

• Alternative to surgery: Consider sirolimus as a first-line option for diffuse microcystic lymphangiomas of the tongue, thus avoiding the functional complications and high recurrence rate of partial glossectomy.
• Safety and prophylaxis: Due to the myelosuppressive effect of sirolimus, the systematic prescription of trimethoprim-sulfamethoxazole is essential to prevent the risk of Pneumocystis pneumonia.
• Multidisciplinary follow-up: The treatment requires close collaboration with a pediatric oncology department for monitoring residual blood levels (target: 6-10 ng/mL) and complete blood count.

Technical lexicon of the study

Circumscribed lymphangioma: Clinical term referring to lymphangiomas of the tongue that are almost exclusively microcystic, often manifesting as superficial vesicular nodules.

Microcystic : Classification of a lymphatic malformation characterized by tissue cavities with a volume of less than 2 cm³.

Macroglossia: Pathological increase in tongue volume, which can lead to airway obstruction, exclusive nasal breathing, and speech disorders.

mTOR inhibitor: Pharmacological class (e.g. sirolimus) acting by inhibiting proliferation and inducing atrophy of lymphatic tissue.

Veno-lymphatic malformation: Radiological diagnosis (established here by T2-weighted MRI) identifying a malformative lesion involving both venous and lymphatic networks.

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