Collision tumor of the thyroid – a challenge during the COVID-19 pandemic

Some of the patients with anaplastic thyroid carcinomas have a coexistent differentiated thyroid cancer, sustaining the hypothesis that this cancer may develop from more differentiated tumors. We describe a case with a collision tumor of the thyroid, defined as a neoplastic lesion composed of two distinct cell populations, with distinct borders. The patient presented during the COVID-19 pandemic with dysphonia, dyspnea, multinodular goiter and a painless, rapidly enlarging, left cervical swelling. She had been first time diagnosed with left nodular goiter in 2007, with an indication for surgery, which she declined. After partial excision of the left latero-cervical adenopathy, the pathological analysis showed massive lymph node metastasis from anaplastic thyroid cancer. A total thyroidectomy was done; the postoperative pathological exam identified a papillary thyroid microcarcinoma in the right lobe and an anaplastic thyroid cancer in the left lobe. Postoperatively, levothyroxine treatment was started and the patient was referred to radiotherapy. This case highlights the importance of urgent management of some cases with compressive multinodular goiter, even during the COVID-19 pandemic.

Four-Cell Population Collision Tumor of the Scalp: A Case Report and Review of Literature

Background: Most cases of collision tumors (CTum) usually present with 2 histologic cell types. We report a unique CTum case comprised of 4 cell populations. Additionally, we performed a systematic review of the current literature published on head and neck collision tumors (HNCTum). Methods: Eighty-one-year-old male presents with a scalp lesion of several years’ duration. PET/CT scan demonstrated increased uptake in the scalp. Wide local excision with free flap reconstruction was performed and tissue pathology reviewed. Database search of HNCTum was performed and reported. Results: Specimen histopathology consisted of melanoma, squamous cell carcinoma, basal cell carcinoma, and pleomorphic dermal sarcoma. Thirty-one articles met inclusion criteria: 11 thyroid, 7 cutaneous, 7 laryngeal, 2 lymph nodes, 2 salivary gland, 1 glottic, 1 maxillary sinus, and 1 tonsil. Conclusion: We present a highly unique CTum case of 4 different cell populations. The systematic review provides a comprehensive report of HNCTum in literature.

Case Report: Cutaneous Pleomorphic Lymphangiosarcoma in a Dog Exhibiting Features of Human Composite Hemangioendothelioma

Background: Angiosarcomas are a broad category of vascular origin neoplasms that are poorly characterized in veterinary species. Lymphangiosarcoma (LAS) is an uncommon type of angiosarcoma reported in humans and canines arising from lymphatic endothelium. LAS can be differentiated from other angiosarcomas in dogs based on expression of Prospero-related homeobox gene-1 (PROX-1) or lymphatic vessel endothelial receptor-1 (LYVE-1). Composite hemangioendothelioma (CHE) is a rare angiosarcoma subtype described in people and characterized by a variable biologic behavior and infrequent metastasis. This variant of angiosarcoma histologically combines features of retiform hemangioendothelioma and epithelioid hemangioendothelioma. Information regarding the cytologic and histopathologic appearance and clinical course of dogs with vascular tumors that exhibit features of CHE are unknown. Here, we report a case of pleomorphic LAS with features of CHE arising in a dog and treated with surgery and adjuvant chemotherapy.Case presentation: A 10-year-old intact male Labrador retriever presented with an approximately 6-cm-diameter cutaneous mass caudal to the left elbow that was progressively growing over 1.5 years. On physical examination, palpable extensions were identified coursing proximally over the triceps with concurrent loco-regional peripheral lymphadenopathy. Fine needle aspirates (FNA) and cytologic assessment of the cutaneous mass, left prescapular, and accessory axillary lymph nodes reported that this appeared to be a metastatic epithelial neoplasm, although a mixed carcinoma or collision tumor could not be excluded. An incisional biopsy of the mass was submitted for histopathology and was consistent with a well-differentiated angiosarcoma with features of CHE. The neoplasm expressed vimentin, CD31, von Willebrand factor (vWf), and PROX-1, supporting the diagnosis of LAS. Complete staging was performed, and no additional metastatic lesions were identified. Left forelimb amputation and lymph node removal were performed. Based on the diagnosis of metastatic LAS, doxorubicin chemotherapy was administered. 7 months post-amputation, the tumor recurred at the amputation site without evidence of metastatic disease.Conclusion: This report describes a malignant, locally aggressive lymphatic origin vascular tumor in a dog, with features consistent with descriptions of CHE in humans. Cytologic features in this case were discordant with its true mesenchymal etiology, obfuscating diagnosis. The morphologic features of the mesenchymal neoplastic population and immunohistochemistry (IHC) labeling ultimately supported a diagnosis of pleomorphic LAS with features of CHE.