Role of Stereotactic Radiosurgery in Intracranial Histiocytosis: a Systematic Review of Literature of an Emerging Modality for Localized Disease

Successful treatment of medically and surgically refractory lymphocytic hypophysitis with fractionated stereotactic radiotherapy: a single-center experience and systematic literature review

PURPOSE

To explore the potential role of focused radiotherapy in managing the lymphocytic hypophysitis (LH) refractory to medical therapy and surgery.

METHOD

A systematic literature review was conducted following PRISMA guidelines to identify the studies on radiation treatment for hypophysitis, along with the experience in our institution.

RESULTS

The study included eight patients, three from our institution and five from existing literature. The age at presentation ranged from 37 to 75 years old, with a median age of 58. The presenting symptoms involved headache in seven patients and diplopia in two patients. Pre-radiation visual field defects were noticed in four patients. All patients exhibited variable degrees of hypopituitarism before radiation, with oral corticosteroids being the initial medical treatment. Immunosuppressive therapy was attempted in two patients prior to radiation. Seven patients had a history of transsphenoidal surgery with a histologically confirmed LH. Three patients underwent stereotactic radiosurgery (SRS), while the remaining received FSRT, with a mean irradiation volume of 2.2 cm3. A single-session total dose of 12 -15 Gy was administered in the SRS group. In the FSRT group, doses ranged from 24 to 30 Gy with a median dose of 25 Gy, delivered in 2 Gy fractions. Four patients achieved a resolution of visual field defects, while another two patients demonstrated improvement in their associated focal neurologic deficits. No change in pre-existing endocrine status was shown after radiation, except in one patient. Clinical response was achieved in seven patients after a single course of radiation, while one patient required the second course. Six patients remained stable on low-dose glucocorticoid during at least a 12-month follow-up period, and one discontinued it entirely without experiencing relapse. Three patients demonstrated a complete radiologic response, while the remaining showed a partial radiologic response.

CONCLUSIONS

Focused radiation, including FSRT, can play a role in symptomatic relief, effective mass shrinkage, and minimizing radiation exposure to critical surrounding structures in patients with refractory LH. However, further research efforts are necessary to better clarify its effects and optimal dose planning.

Stereotactic Radiosurgery for Localized Cranial Langerhans Cell Histiocytosis: A Single Institution Experience and Review of Literature

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare idiopathic disease characterized by the clonal proliferation of Langerhans histiocytes in various parts of the body and capable of leading to organ damage and tumor formation. Reports of cranial LCH in the adult population are extremely rare. Although surgery remains the preferred option for localized LCH lesions, the role of stereotactic radiosurgery (SRS) is emerging.

OBJECTIVE

To retrospectively review a rare case series to determine the safety and effectiveness of SRS for patients with localized cranial LCH.

METHODS

We retrospectively reviewed histopathologically confirmed cases of localized cranial LCH treated with SRS at our institute in the adult population between January 2005 and September 2022. Five patients were identified with a median age of 34 years (19-54 years). The tumor location was in the pituitary stalk in 3 patients, the orbit in one patient, and the parietal skull in one patient. The median target volume was 2.8 cc (range: 0.37-6.11). Treatment was delivered in a single fraction in 4 patients (median margin dose of 8 Gy, range: 7-10 Gy) and in 3 fractions (22.5 Gy) in 1 patient. The median follow-up was 12 years (range: 4-17). None of the patients required craniotomy for tumor debulking before or after SRS.

RESULTS

The local tumor control rate for the lesions was 100%. All 3 patients with LCH in the pituitary stalk had diabetes insipidus at the initial presentation and developed panhypopituitarism after SRS. Diabetes insipidus was not improved after SRS. The other 2 patients presented no adverse radiation effects. Based on the literature review, our case series was the largest retrospective series on SRS for localized cranial LCH, with the longest median follow-up.

CONCLUSIONS

SRS for patients with localized cranial LCH was a safe and effective treatment modality in this case series. Larger studies are encouraged to validate the role of SRS in the treatment of localized cranial LCH.