THU672 Fungating And Inflammatory Anaplastic Thyroid Carcinoma In A 64-Year Old Filipino

Disclosure: R.M. Tarrazona - Dominisac: None. M.C. Isidro: None. Background: Anaplastic Thyroid Carcinoma is a rare and lethal undifferentiated thyroid cancer that occurs in less than 2% of all thyroid malignancies. In the Philippines, this rare entity has an estimated incidence of 0.7%. Its aggressive nature is strikingly significant because it carries a poor prognosis with a median survival of 5-6 months. An exceptionally rare presentation of an Anaplastic Thyroid Carcinoma is a fungating, exophytic and inflammatory type. Case Summary: This is a case of a 64-year old female with a 2 x 2 cm erythematous patch at her anterior neck. There is progressive enlargement of the reddish neck lesion associated by burning sensation with subsequent development whitish nodules with purulent exudate. The nodules were fragile with noted bleeding on minimal manipulation. Initial impression was anterior neck cellulitis and she was given 7 days of IV antibiotics with no resolution of the lesion. Neck CT scan showed a multinodular heterogeneously enhancing mass in the left neck region measuring 6.3 x 5.2 x 5.5 cm. A core needle biopsy of the mass revealed malignant cells present: anaplastic carcinoma vs squamous cell carcinoma, with immunohistochemical stains: PAX 8 positive, p63 negative, CK 5/6 negative, BRAF negative, TTF-1 focally positive. The patient underwent tumor debulking surgery with tracheostomy. The gross specimen was sent for histopathologic examination and finally revealed Anaplastic Thyroid Carcinoma. Conclusion: The case reported was a diagnostic dilemma early during the clinical presentation due to presence of rapidly enlarging, inflammatory and fungating anterior neck mass with presence of whitish nodules with purulent exudates, bleeding and pain. She was initially treated as an abscess only to discover presence of malignancy upon further work-up. Anaplastic thyroid cancer is the most advanced and aggressive thyroid malignancy. It is very rare and the atypical fungating presentation of this ATC makes it an exceptionally rare entity. Fungating wounds are the result of cancer cells infiltrating and invading the cutaneous structure. This case report highlights the importance of harnessing a high level of clinical suspicion for anaplastic thyroid cancer even in atypical looking anterior neck mass to ensure prompt definitive diagnosis and improve overall prognosis. Presentation: Thursday, June 15, 2023