Post-surgical Thyroid Bed Pyoderma Gangrenosum Mimicking Recurrent Papillary Thyroid Carcinoma

Area of Science:

• Dermatology
• Endocrinology
• Pathology

Background:

• Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis causing ulcers, often at trauma sites.
• While typically cutaneous, PG can affect any organ, but thyroid bed involvement is unreported.
• Systemic neutrophilic diseases may present with a cutaneous phenotype like PG.

Observation:

• A patient with breast PG developed suspicious thyroid nodules post-thyroidectomy.
• Initial fine-needle aspiration suggested papillary thyroid cancer (PTC).
• Post-surgery, imaging revealed suspicious thyroid bed lesions, initially mimicking PTC recurrence.

Findings:

• Thyroid bed lesions showed neutrophilia on fine-needle aspiration, unlike typical PTC.
• Undetectable thyroglobulin levels and elevated inflammatory markers suggested an inflammatory, not neoplastic, process.
• High-dose methylprednisolone treatment led to lesion reduction, confirming PG infiltration.

Implications:

• This case highlights thyroid bed PG as a rare postsurgical differential diagnosis.
• Endocrinologists should consider PG in patients with prior PG history and unexplained thyroid bed findings.
• PG may represent a broader spectrum of systemic neutrophilic diseases beyond the skin.