Dr. Jared Gardner and Dr. Halek Cavas present Case 7, a pathology lecture case focusing on a red-purple cheek nodule in a 75-year-old man. The tumor is a highly aggressive, high-grade neoplasm composed of atypical spindle cells with extensive necrosis. Although the presence of spindle cells within blood-filled spaces initially raises consideration for Kaposi Sarcoma (KS), the dramatic cellular atypia and the unusual location (sun-damaged head and neck of an elderly patient) are strong indicators against KS. The final diagnosis is Angiosarcoma (AS), a potentially fatal vascular malignancy. Dr. Gardner stresses that diagnosing solid, spindled Angiosarcomas often requires careful searching for areas of characteristic, infiltrating, interconnected vascular channels lined by malignant endothelial cells, particularly at the periphery of the lesion, and warns against diagnostic pitfalls like CD34 negativity and keratin positivity in epithelioid variants.
Oregon Pathologist Association Case 7: Angiosarcoma of the Cheek
0:11 Case Introduction: Dr. Jared Gardner and Dr. Halek Cavas review Case 7: a red-purple cheek nodule in a 75-year-old man, necessary because the original lecture video corrupted.
0:49 Initial Histology: The tumor is highly cellular, multi-nodular, extending deep into the subcutis and skeletal muscle, showing large zones of necrosis, significant atypia, and high mitotic activity, indicating a very high-grade aggressive tumor.
1:47 Differential Diagnosis: The presence of spindle cells in fascicles with little cracks and blood-filled spaces initially suggests Kaposi Sarcoma (KS).
2:04 Ruling out KS: The tumor is too ugly and atypical for typical KS. Furthermore, KS is usually associated with AIDS/immune suppression or presents on the lower legs of elderly patients (not the face).
2:43 Final Diagnosis: Angiosarcoma (AS): The tumor is a solid and cellular spindled angiosarcoma. The location and age of the patient (sun-damaged head and neck of an old person) make AS the primary diagnosis until proven otherwise.
3:15 Classic AS Feature: The crucial diagnostic feature, often found at the periphery of the tumor mass, is the formation of infiltrating, irregular, interconnected vascular channels lined by atypical, malignant endothelial cells.
4:34 Diagnostic Challenges (Solid Variants): Angiosarcomas can be very cellular and solid, sometimes mimicking KS or other sarcomas. Epithelioid AS is particularly tricky as it can be keratin positive and mistaken for poorly differentiated carcinoma.
5:24 Preferred IHC Markers: Angiosarcoma typically stains with vascular markers, primarily ERG and CD31. Key Takeaway: CD34 can be negative, presenting a major diagnostic pitfall.
5:45 Biopsy Risk: Shave biopsies are treacherous. Endothelial atypia in small samples from the elderly, sun-damaged head/neck should raise high suspicion for AS, requiring a larger sample for rule-out.
7:06 Aggressive Infiltration: The tumor is shown infiltrating widely beyond the main mass, including perineural invasion (0:07:06). This wide infiltration makes margin assessment, especially during frozen section, very difficult.
7:51 Location: Most angiosarcomas are cutaneous (in the skin). Rare exceptions include primary tumors in the breast (unrelated to radiation), the right atrium of the heart, or occasionally the liver or spleen.