What is the recommended management for a 30-year-old individual with a BMI of 20.1 kg/m², presenting with headache, visual disturbance, and head pain, who has a stable enhancing lytic lesion in the right occipital skull base, normal laboratory findings, and no acute intracranial abnormality?

Management of Stable Lytic Skull Base Lesion with Headache and Visual Symptoms

This patient requires immediate comprehensive workup to exclude multiple myeloma and other systemic diseases, followed by tissue diagnosis if plasma cell dyscrasia is ruled out, as lytic skull lesions demand definitive pathologic diagnosis to guide treatment. 1

Immediate Diagnostic Workup

Essential Laboratory Studies

• Order a complete plasma cell dyscrasia panel immediately, including serum protein electrophoresis (SPEP) with immunofixation electrophoresis (SIFE), serum free light chain (FLC) assay, quantitative immunoglobulin levels, and 24-hour urine for total protein with urine protein electrophoresis (UPEP) and urine immunofixation electrophoresis (UIFE) to exclude multiple myeloma and solitary plasmacytoma. 1
• Multiple myeloma and solitary plasmacytoma are among the most common causes of lytic skull lesions in adults, and the presence of more than 1 focal lesion on MRI characterizes symptomatic disease requiring therapy. 1
• The patient's normal metabolic panel does not exclude plasma cell dyscrasia, as these conditions are diagnosed through specific protein studies, not routine chemistry panels. 2

Advanced Imaging Requirements

• Obtain whole-body low-dose CT (WBLD-CT) immediately to determine whether this represents a solitary lesion or part of disseminated disease. 1
• WBLD-CT detects 60% more relevant findings than conventional X-rays and provides superior evaluation of cortical bone detail and areas at risk of fracture. 1
• Whole body CT with low-dose protocols can detect lesions with less than 5% trabecular bone destruction, making it the first-line diagnostic imaging procedure for lytic bone disease. 3
• The existing MRI with contrast is appropriate for soft tissue characterization, but WBLD-CT is essential for complete skeletal survey. 1, 3

Bone Marrow Evaluation

• If plasma cell dyscrasia panel shows any abnormality, proceed immediately to bone marrow aspiration and biopsy with flow cytometry, as this is mandatory for diagnosing solitary plasmacytoma. 1
• Flow cytometry can detect occult bone marrow disease in 49-68% of patients with apparent solitary plasmacytoma, and patients with occult bone marrow involvement have significantly higher progression rates to multiple myeloma (71-72% versus 8-12.5%). 1

Tissue Diagnosis Strategy

When to Biopsy

• If plasma cell dyscrasia workup is negative, obtain tissue diagnosis through biopsy to characterize this enhancing lytic lesion. 1
• Adequate tissue must be obtained for both histology and molecular testing, as integrative diagnosis may require ancillary studies. 1
• Expert pathology review is critical, particularly if sarcoma is suspected, as accurate diagnosis is critical for treatment planning. 1

Critical Surgical Consideration

• Never perform internal fixation of a pathological fracture before obtaining a biopsy, as this is a critical error that can compromise diagnosis and treatment. 1
• While this patient does not currently have a fracture, this principle applies to any surgical intervention on the lesion. 1

Differential Diagnosis Considerations

Benign Skull Base Tumors

• Skull base leiomyomas and angioleiomyomas (average size 2.75 cm, range 0.7-7.7 cm) present with location-specific symptoms including headaches, visual deficits, and cranial nerve deficits. 2, 4
• These benign smooth muscle tumors achieved gross total resection in 81.8% of cases, with median clinical follow-up of 11 months showing good outcomes. 2
• The most common skull base locations for these tumors are cavernous sinus (13 patients), external auditory canal (9 patients), and sella/tuberculum (4 patients). 2
• Headache occurred in 9 of 34 patients with skull base leiomyomas/angioleiomyomas, with symptoms correlating with lesion location. 2

Malignant Considerations

• Multiple myeloma commonly presents with multiple osteolytic lesions, particularly at the skull level, appearing as numerous well-circumscribed punched-out lytic bone lesions without reactive bone formation. 3
• Lytic skull lesions range from benign conditions to aggressive malignant lesions such as lymphomas or metastases, making early and correct characterization crucial. 5

Symptom Management During Workup

Headache Management

• The patient's headache and head pain require symptomatic management while diagnostic workup proceeds. 6
• CT is superior to MRI for most osseous lesions of the cranial vault and skull base when evaluating headaches secondary to cranial disorders. 6

Visual Disturbance Evaluation

• Visual disturbances with an occipital skull base lesion near the foramen magnum warrant careful monitoring, though lesions in the inferior occipital bone typically do not directly affect the visual cortex. 7
• The visual symptoms may be related to increased intracranial pressure or referred pain rather than direct cortical involvement. 7

Treatment Algorithm Based on Diagnosis

If Multiple Myeloma/Plasmacytoma Confirmed

• Stage according to Durie-Salmon classification using hemoglobin, calcium, M-protein levels, bone lesions, and renal function. 2
• MRI and/or PET scan refine staging: single plasmacytoma indicates stage IA, <5 focal lesions indicates stage IB, 5-20 focal lesions indicates stage IIA/B, and >20 focal lesions indicates stage IIIA/B. 2
• Cytogenetics by conventional karyotyping or FISH analysis is a major prognostic factor; del(13), t(4;14), and del(17p) are associated with poorer outcomes. 2

If Benign Tumor Confirmed

• Surgical resection is the standard treatment for symptomatic skull base leiomyomas and angioleiomyomas, with gross total resection achieved in 81.8% of cases. 2
• Surgical approach depends on location; retrosigmoid approach was successful for internal auditory canal lesions with preservation of cranial nerve function. 2
• Technical aids including preoperative functional MR, surgical microscope, neuro-navigation, and intraoperative brain mapping optimize surgical resection. 2

Common Pitfalls to Avoid

• Do not assume stability on imaging means benign disease—multiple myeloma can have stable-appearing lesions that still require treatment. 1
• Do not rely on normal routine laboratory findings to exclude serious pathology—specific plasma cell studies are essential. 1
• Do not proceed with observation alone without completing the diagnostic workup, as this delays potentially critical treatment. 1
• Do not perform conventional X-rays as the primary skeletal survey, as lytic lesions only become visible after more than 50% of trabecular bone has been lost. 1