Objective

1) Perform a meta-analysis of the available data on the outcomes of stereotactic radiosurgery (SRS) for the treatment of temporal bone glomus tumors (GT), and 2) evaluate the collective outcomes of SRS treatment with respect to tumor control.

Data sources

A thorough literature search of the published English-language literature from 2011 to 2016 was performed in PubMed, Ovid, and Cochrane databases using the keywords ("Gamma Knife" or "CyberKnife" or "linear accelerator" or "radiosurgery") and ("glomus jugulare" or "jugular paraganglioma" or "glomus tympanicum").

Study selection

Studies reporting outcomes of SRS for temporal bone GT were included.

Data extraction

Of 45 articles found, 15 studies met our inclusion and exclusion criteria and were selected for qualitative and quantitative analyses totaling 511 patients.

Data synthesis

Average margin dose, modality, isodose line, volume decrease, follow-up duration, and tumor control rate data were extracted and analyzed.

Conclusion

Gamma Knife was the most commonly implemented radiosurgery modality and was used in eight studies. The mean marginal dose varied between 13.2 and 20 Gy. The pooled tumor control rate was 95.4% (95% CI: 93.6-97.2%) over a median follow-up duration ranging between 27.4 and 148 months. Clinical data on outcomes of SRS for the treatment of GTs are sparse and primarily limited to single institutional analyses, with considerable variation in tumor volume and follow-up duration. This meta-analysis provides an in-depth analysis of the available data in the literature and reviews the reported outcomes. Future studies on SRS for GT should include data on tumor growth before radiation as well as follow-up periods sufficiently long to identify true tumor control.

Background

Glomus tumors are difficult to manage surgically because they are vascular tumors that are topographically associated with important vascular and neuronal structures. Hence, there is a strong risk of incomplete resection and a high morbidity rate. In addition, they grow slowly. Recent treatments have increasingly involved a combination of surgical resection and radiosurgery. We present our experience in treating glomus tumors of the skull base with stereotactic radiosurgery as an upfront therapy.

Methods

We analyzed data from 13 consecutive patients with glomus tumors that were initially treated with stereotactic radiosurgery in our institute from February 2010 to April 2012. The tumor control rate, resolution of symptoms, and the complication rate were tabulated.

Results

All patients were female with a median age of 63 (mean 62.7+/-14.6 years). The median treatment dose was 25.8 Gy (27.6 Gy +/- 9.5 Gy) and the median tumor volume 10.4 mL (9.2 +/- 6.5). The median follow-up was 47.4 months (51.8+/-11.2 months, range 31-74). The tumor control rate was 92.3%; 46.7% of the patients had noticeable tumor shrinkage. This happened at a median interval of 17 months (18.7+/-6.8) after treatment. Most patients with tinnitus had resolution of their symptoms (87.5%). Four patients presented with new symptoms and four patients with worsening of pre-existing symptoms. The time course of symptomatic improvement followed that of tumor size reduction. However, there was no statistical correlation between the amount of tumor reduction and symptomatic relief.

Conclusion

Stereotactic radiosurgery (SRS) is an effective upfront treatment option in the management of glomus tumors.

We present a patient with a painful, mobile nodule on the elbow. The nodule was skin-colored and had no punctum or discharge. It was excised and histopathology showed that the lesion was a glomangioma, or glomuvenous malformation. This is a neoplasm that arises from the glomus body, a thermoregulatory neurovascular structure. The glomus body is composed of glomus cells, vascular cells, and smooth muscle cells. Three subtypes of neoplasms may arise from the glomus body, depending on the extent to which they involve the three types of cells. They include glomus tumors, glomangiomas/glomuvenous malformations, and glomangiomyomas. This case was unusual in that it did not present with surface color change to indicate a vascular component.

Glomus tumors are benign tumors of the skin. Clinically, these tumors can present as solid, painful subcutaneous nodules, frequently seen on the hand (particularly subungual region). Glomangiomyomas are the least common histological type of glomus tumor. In the literature, there are only a few glomangiomyoma cases of the forearm location. We report a patient with a painful nodule, diagnosed as glomangiomyoma. Surgical excision was performed and no recurrence was observed after 5 years' follow-up.

Glomus tumor is a rare benign vascular hamartoma derived from the modified smooth muscle cells of the glomus body. Paroxysmal pain is the leading symptom. A 78-year-old woman presented at our clinic with a 50-year history of a slow growing painful purple blue tender nodule under the right fourth finger nail. Dermoscopy and magnetic ressonance confirmed the presence of a large subungual tumor and total surgical excision was performed after partial nail plate avulsion. Histologic examination confirmed a glomus tumor. After 1 year of follow-up, the nail grew with normal shape and neither complications nor recurrence were observed.

We present a patient with a painful glomus tumor of the right upper arm.

Pericytes are modified smooth muscle cells that closely enwrap small blood vessels, regulating and supporting the microvasculature through direct endothelial contact. Pericytes demonstrate a distinct immunohistochemical profile, including expression of smooth muscle actin, CD146, platelet-derived growth factor receptor β, and regulator of G-protein signaling 5. Previously, pericyte-related antigens have been observed to be present among a group of soft tissue tumors with a perivascular growth pattern, including glomus tumor, myopericytoma, and angioleiomyoma. Similarly, malignant tumor cells have been shown to have a pericyte-like immunoprofile when present in a perivascular location, seen in malignant melanoma, glioblastoma, and adenocarcinoma. Here, we examine well-differentiated liposarcoma specimens, which showed some element of perivascular areas with the appearance of smooth muscle (n = 7 tumors). Immunohistochemical staining was performed for pericyte antigens, including smooth muscle actin, CD146, platelet-derived growth factor receptor β, and regulator of G-protein signaling 5. Results showed consistent pericytic marker expression among liposarcoma tumor cells within a perivascular distribution. MDM2 immunohistochemistry and fluorescence in situ hybridization for MDM2 revealed that these perivascular cells were of tumor origin (7/7 tumors), whereas double immunohistochemical detection for CD31/CD146 ruled out an endothelial cell contribution. These findings further support the concept of pericytic mimicry, already established in diverse malignancies, and its presence in well-differentiated liposarcoma. The extent to which pericytic mimicry has prognostic significance in liposarcoma is as yet unknown.

An 81-year-old man presented to the dermatology clinic with a painful lesion on his chest. The nodule would occasionally bleed and leak serous fluid for 10 years. Physical examination revealed an unspecified nodule with two superimposed nodules. A deep shave biopsy of the lesion was obtained and expressed a solid-cystic dermal neoplasm that was comprised of an admixture of cell types. Through the presenting clinical and histological features seen, a final diagnosis of nodular hidradenoma was made.