Background: Typically arising from skeletal muscle, rhabdomyosarcoma (RMS) rarely may be found in the head and neck. Here, we report a rare occurrence of fatal, aggressive RMS in association with pituitary corticotropinoma.
Case: A 52-year-old male veteran presented with 1-year history of hypertension, diabetes mellitus, vertebral fractures, central obesity, muscle wasting, and multiple pulmonary embolisms. Based on the clinical and biochemical findings, he was diagnosed with Cushing’s disease. Pituitary MRI demonstrated a hypoenhancing heterogeneous 16x15x12 mm sellar mass which was resected by trans-sphenoidal surgery (TSS). During TSS, 2 distinct tumor masses were identified—a firm sphenoidal mass with dural/bony invasion, and a soft adenomatous intrasellar mass contiguous through a small opening in the sellar bone.
Histopathologic analysis of the intrasellar component confirmed a pituitary corticotropinoma with strong ACTH staining and MIB-1 proliferative index (MIB-1) < 1%. By contrast, the tumor in the sphenoid sinus was a high grade, pleiomorphic RMS consisting of a malignant spindle cell neoplasm with occasional rhabdoid phenotype, brisk mitotic activity, high MIB index and areas of necrosis with strong positivity for desmin and MYF4. Molecular genetic profiling showed that corticotropinoma and RMS elements derived from the same cytogenetically abnormal founder clone, yet subsequently diverged as evidenced by distinct somatic p53 mutations in the corticotropinoma (c.764T>A, c.757A>C) and RMS sub clones (c.736A>G).
Pan CT, MRI brain and bone scan were negative for other primary/metastatic foci. A 18F-FDG PET study detected increased metabolic activity within the sphenoid mass. He was started on chemotherapy with etoposide, vincristine and cyclophosphamide, but the disease relentlessly
progressed with an extension to bilateral optic nerves, internal carotid arteries, ethmoid sinus and nasal cavity. The patient felt that he cannot fight a “losing battle,” opted for home hospice and eventually died in 2 months.
Conclusions: In nontextbook appearance of tumors, a high index of suspicion for unusual tumors like rhabdomyosarcoma arising within sella/sphenoid sinus, is needed for an early intervention. Analysis of genomic data in these tumors may suggest treatment matched to specific tumor mutations.
