Differential Diagnosis for a 39-year-old Lady with Neck Swelling and Palpitations

Single Most Likely Diagnosis

• Thyroiditis (De Quervain’s thyroiditis): The patient's recent history of viral infection, followed by neck swelling, pain, and symptoms of hyperthyroidism such as heat intolerance, increased sweating, and palpitations, points towards thyroiditis, specifically De Quervain’s thyroiditis, as the most likely diagnosis. The absence of a palpable thrill, bruit, or significant lymphadenopathy, along with symmetrically enlarged thyroid glands, further supports this diagnosis.

Other Likely Diagnoses

• Graves’ Disease: Given the family history of Graves’ disease and the patient's symptoms of hyperthyroidism (heat intolerance, increased sweating, palpitations), Graves’ disease is a plausible diagnosis. However, the absence of specific signs like exophthalmos, lid lag, and pretibial myxedema, and the recent viral infection, make thyroiditis more likely.
• Subacute Thyroiditis: This condition can present with neck pain, swelling, and symptoms of hyperthyroidism, similar to De Quervain’s thyroiditis. The distinction often relies on the specific characteristics of the thyroid pain and the phase of the illness (initial hyperthyroid phase, followed by hypothyroid phase, and then return to euthyroidism).

Do Not Miss Diagnoses

• Thyroid Storm: Although less likely given the patient's current presentation, thyroid storm is a life-threatening condition that requires immediate recognition and treatment. It can present with exaggerated symptoms of hyperthyroidism, including severe tachycardia, fever, and altered mental status.
• Mediastinal Mass or Thyroid Cancer: Although rare, a mediastinal mass or thyroid cancer could cause neck swelling and systemic symptoms. The absence of significant lymphadenopathy, a palpable mass, or deviation of the trachea makes these less likely, but they should not be entirely ruled out without further investigation.

Rare Diagnoses

• Riedel’s Thyroiditis: A rare form of chronic thyroiditis characterized by a hard, fibrous thyroid gland that can cause compressive symptoms. The patient's presentation does not strongly suggest this diagnosis, given the lack of significant tracheal deviation or compressive symptoms.
• Painless Thyroiditis: Another form of thyroiditis that can cause hyperthyroid symptoms without significant thyroid pain. The recent viral infection and presence of thyroid pain make De Quervain’s thyroiditis more likely, but painless thyroiditis remains a consideration in the differential diagnosis.