Management of calvarial osteomyelitis and persistent cerebrospinal fluid leak following transcranial resection of an invasive pituitary macroadenoma: A case report

Johnson A*

Group Clinical Pharmacist, Kauvery Hospital, Trichy, Tamil Nadu

*Correspondence

Abstract

Invasive pituitary macroadenomas (KNOSP Grade 4) present significant surgical challenges due to their extension into the cavernous sinus and encasement of neurovascular structures. This case report details the management of a 34-year-old male who presented with a persistent cerebrospinal fluid (CSF) leak and surgical site infection three months following a right pterional craniotomy. Imaging and histopathology confirmed osteomyelitis of the bone flap caused by Staphylococcus aureus. The patient underwent successful wound debridement, excision of the infected bone, and targeted antibiotic therapy, highlighting the importance of aggressive source control in post-craniotomy infections.

Keywords: Pituitary Macroadenoma; KNSOP Grade 4; Osteomyelitis; CSF leak; Neuroendocrinology.

Introduction

Invasive Pituitary Macroadenoma

Pituitary adenomas >10 mm are classified as macroadenomas. Invasiveness is often graded using the Hardy-Wilson and KNOSP scales. A KNOSP Grade 4 classification indicates high-grade invasiveness where the tumor completely encases the intracavernous Internal Carotid Artery (ICA), making complete surgical resection difficult and increasing the risk of postoperative complications such as CSF leaks.

Case Presentation

A 34-year-old male, presented with a history of clear fluid discharge from the surgical site and a non-healing wound for three months.

  • Primary Diagnosis: Invasive Pituitary Macroadenoma (Hardy-Wilson Grade 4E, KNOSP Grade 4, Bilateral).
  • Surgical History: The patient underwent a right pterional craniotomy and near-total decompression of the tumor on January 15, 2025, at an external facility.
  • Presenting Complaint: Persistent postoperative CSF leak and wound dehiscence refractory to conservative management.

Clinical Examination

On admission, the patient was conscious and oriented (GCS 15/15). Local examination of the right fronto-temporal region revealed a surgical wound with signs of active infection and visible discharge. There were no focal neurological deficits, and the patient was afebrile at the time of examination.

Diagnostic Imaging

A CT scan of the brain performed on January 2, 2026, revealed the following:

  • Tumor Status: A hyperdense mass lesion in the sella with suprasellar extension and encasement of the right ICA.
  • Bone Pathology: A postoperative defect in the right fronto-temporo-parietal region showing thickened bone with cortical irregularity.
  • Soft Tissue: Extra-axial hyperdensity with thickening of the adjacent skin and sinus tract formation.
  • Radiological Impression: Features strongly suggestive of osteomyelitis of the bone flap.

Microbiology and Histopathology

  • Pus Culture: Yielded growth of Staphylococcus aureus, a common pathogen in postoperative neurosurgical skin and bone infections.
  • Histopathology: Biopsy of the excised tissue showed bony trabeculae with marrow spaces exhibiting granulomatous inflammation, focal necrosis, and karyorrhectic debris, confirming chronic osteomyelitis.

Therapeutic Management

Surgical Intervention

Given the failure of conservative management and the presence of infected bone (nidus of infection), the patient underwent surgical revision on January 3, 2026. The procedure involved:

  • Wound debridement.
  • Re-exploration of the craniotomy site.
  • Excision of the infected bone flap and removal of granulomatous tissue.

Medical Management

Postoperatively, the patient was managed with a multidisciplinary regimen:

  • Antibiotic Therapy: Intravenous antibiotics were administered to treat the aureus osteomyelitis:
    • Ceftriaxone (Monocef) 2g IV BD for 14 days.
    • Vancomycin 1g IV BD for 7 days.
  • Hormonal Replacement: To address pituitary insufficiency secondary to the invasive adenoma and surgery:
    • Cabergoline 0.25mg (Weekly) for prolactin control.
    • Thyroxin 25mcg (Daily) for hypothyroidism.
  • Supportive Care: Seizure prophylaxis with Levetiracetam (Brevipil) 100mg BD and gastroprotection with Pantocid.

Outcome and Follow-up

The patient demonstrated excellent recovery. The CSF leak ceased immediately post-procedure, and the wound showed signs of healthy healing without soakage. He was discharged in a stable condition with instructions to continue oral antibiotics, hormonal supplements, and antiepileptics. A follow-up was scheduled for January 27, 2026.

The Pituitary Gland: Anatomy and Physiology

The pituitary gland, often termed the “master gland,” is a critical neuroendocrine organ located within the sella turcica of the sphenoid bone at the base of the brain. Despite its small size, it regulates essential physiological processes through the secretion of hormones that control other endocrine glands. It is anatomically and functionally divided into two lobes:

  • The Anterior Lobe (Adenohypophysis): Comprises glandular tissue responsible for synthesizing and releasing major trophic hormones:
    • Growth Hormone (GH): Regulates somatic growth and metabolism.
    • Prolactin (PRL): Stimulates milk production in lactation.
    • Adrenocorticotropic Hormone (ACTH): Stimulates the adrenal cortex to release cortisol.
    • Thyroid-Stimulating Hormone (TSH): Regulates thyroid function.
    • Gonadotropins (LH/FSH): Control reproductive functioning.
  • The Posterior Lobe (Neurohypophysis): An extension of the hypothalamus that stores and releases:
    • Vasopressin (Anti-Diuretic Hormone/ADH): Regulates water retention and blood pressure.
    • Oxytocin: Facilitates uterine contractions and milk ejection.

Discussion

This case illustrates the “double-hit” complication of CSF leak and subsequent osteomyelitis in skull base surgery. Invasive macroadenomas (KNOSP 4) often require aggressive dural opening or have inherent dural defects due to tumor invasion. A persistent CSF leak creates a way for skin flora, such as Staphylococcus aureus, to colonize the bone flap, leading to calvarial osteomyelitis.

Effective management requires a paradigm shift from conservation to radical debridement when bone infection is confirmed. Removal of the infected bone flap (source control) combined with culture-directed antibiotic therapy is the gold standard for achieving cure and preventing intracranial spread (meningitis/abscess). Furthermore, strict adherence to hormonal replacement is vital, as the invasive nature of the tumor and surgical manipulation often compromise pituitary reserve.

Conclusion

Persistent CSF leak post-craniotomy is a significant risk factor for osteomyelitis. Early recognition via imaging (CT/MRI) and prompt surgical removal of infected bone, alongside multidisciplinary endocrine management, are essential for successful patient outcomes.

References

  1. Knosp E, Steiner E, Kitz K, Matula C. Pituitary adenomas with invasion of the cavernous sinus space: a magnetic resonance imaging classification with surgical correlation. Neurosurgery. 1993 Oct;33(4):610-7; discussion 617-8.
  2. Molitch ME. Diagnosis and Treatment of Pituitary Adenomas: A Review. JAMA. 2017 Feb 7;317(5):516-524.
  3. Tamp JP, Choy W, Gupta G. Management of Post-Craniotomy Bone Flap Infections: A Systematic Review. World Neurosurg. 2021;148:112-121.
  4. Lal L. Clinical Summary Report: Post-operative management of invasive pituitary macroadenoma and calvarial osteomyelitis. Hospital Records. 2026 Jan 19. (Internal Institutional Record).
  5. Zhu X, Wu J, Wang H. Diagnosis and Management of Postoperative Cerebrospinal Fluid Leakage after Transsphenoidal Surgery for Pituitary Adenoma. J Craniofac Surg. 2020 Jun;31(4):e338-e341.

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