Humeral metastasis as the only recurrence of a 5-year resected gastrointestinal stromal tumor: a case report

Abstract

Introduction: Gastrointestinal stromal tumors represent the most frequently encountered primary mesenchymal tumors. Whereas the liver and the peritoneum are known to be the preferential metastasis sites, no therapeutic standard has yet been established for the management of bone metastases because of their very low incidence. We report a unique example of a single humerus metastasis of a jejunal gastrointestinal stromal tumor.

Case presentation: We report the case of a 72-year-old European woman whose jejunal gastrointestinal stromal tumor was resected in 2013 and treated during the following 3 years with imatinib (400 mg daily). In 2018, she developed a single humeral bone lesion that was identified as a gastrointestinal stromal tumor metastasis. After 7 months of imatinib intake, reconstructive surgery was performed. Pathologists confirmed the satisfactory histological regression and assessed the complete tumor resection. The patient is still on imatinib maintenance therapy, with no recurrence reported so far. She fully recovered the upper limb function after following an appropriate rehabilitation program.

Discussion: Current literature and published case reports indicate that bones are one of the rarest locations of gastrointestinal stromal tumor metastasis (about 1%), with occurrence mainly in the spine. Patients initially diagnosed with gastrointestinal stromal tumor of the small intestine and stomach are more likely to suffer from bone metastasis, compared with other gastrointestinal stromal tumor locations. The median overall survival rate is higher for patients with isolated bone metastasis compared with those having liver metastasis. Metastasis occurs on average 4 years after the primary, but it may take up to 20 years, emphasizing the need for long-term clinical and radiological monitoring. Although specific guidelines for such cases have not yet been established, we suggest that a multimodal concerted approach involving surgery or radiotherapy associated with tyrosine kinase inhibitor intake should be considered.

Conclusion: Bones are one of the rarest locations of gastrointestinal stromal tumor metastasis. A multidisciplinary collaboration was set up to allow conservative surgery of our patient after several months of imatinib treatment. A year and a half later, the patient is still in complete remission. This specific case supports the concept of an intermediate stage between local and oligometastatic disease that should be managed with a curative aim, as much as possible.

Keywords: Case report; Humeral bone metastasis; Imatinib; Jejunal GIST; Surgery.

Fig. 1

October 2018, magnetic resonance imaging (MRI) scan of the left humerus before treatment. Coronal (a) and axial (b) contrast-enhanced fat-suppressed T1-weighted images. Diaphyseal metastasis with extension to adjacent soft tissue highly enhanced

Fig. 2

February 2019: MRI of the left humerus after 3 months imatinib treatment. Coronal (a) and axial (b) contrast-enhanced fat-suppressed T1-weighted images. See the central necrosis and residual peripheral enhancement

Fig. 3

Macroscopic presentation after anteroposterior opening of the surgical humeral bone resection of 15.5 × 2.4 × 3.8 cm (A): It measured 9 cm on height, and reached the proximal section at 3.5 cm and distal section at 0.8 cm. Note the reactional cortical hypertrophy associated. Histological presentation at low magnification (Hematoxylin-eosin stain (HE stain), ×0.5 magnification, B Tumoral area presented as a heterogeneous aspect including hemorrhagic and fibrous modifications

Fig. 4

Histologic features: Hematoxylin-eosin stain (HE stain), ×2 (A) and ×10 magnification (B). Post-therapy regression presented as large fibrous cicatricial sheets containing focal areas of monomorphic spindle cells poorly atypical. Reduction and thickness of the cortical bone with reactional ossification were associated

Fig. 5

A–D Immunohistochemistry markers (×10 magnification): immunohistochemistry profile with DOG1 (A), CD117 (B), and CD34 (C) strong positivity combined with typical morphologic aspect of spindle cells (D) confirmed of a GIST. Signal detection system EnVision FLEX + DAKO. Automate DAKO OMNIS

Fig. 6

February 2020, postsurgery clinical presentation and functional examination. In June 2020, more than 1 year after the surgery, the patient fully recovered the upper limb function, the allograft is well integrated, and no recurrence is reported

Fig. 7

June 2020 examination with standard X-ray (A) and 3D-computerized tomography reconstruction (B)