Primary thyroid sarcomas (PTS) are an incredibly uncommon type of thyroid cancer. Undifferentiated pleomorphic sarcomas of the thyroid (UPS-T) are extremely rare subtypes of thyroid sarcoma with no defined cell differentiation. Here, we report the case of a 60-year-old female with a two-year history of hypothyroidism who presented to our hospital with productive cough, dyspnea, and diffuse facial edema for two weeks. Her chest computed tomography (CT) scan revealed a large anterior mediastinal mass and multiple bilateral pulmonary nodules. Her thyroid ultrasound showed two hypoechoic nodules, while a CTvenogram of the right upper extremity showed superior vena cava and the right brachiocephalic vein obstruction, which was relieved with angioplasty. A biopsy of the anterior mediastinal mass showed poorly differentiated pleomorphic thyroid sarcoma. The patient was not a candidate for inpatient chemo-or radiotherapy because of her overall medical condition. One week later, she developed worsening respiratory failure, was intubated and transferred to the intensive care unit (ICU), where she passed away two days later.

Spontaneous primary tumor regression, or burned-out tumors, refers to the presence of a metastatic tumor with the histological regression of the primary lesion. The burned-out phenomenon has been reported in various malignancies, with testicular germ cell tumors (GCTs) accounting for a significant share of these cases. However, burned-out testicular tumors are a rare clinical phenomenon and are generally difficult to diagnose, as there is no evidence of primary testicular cancer. Here, we describe the case of a 42-year-old male who presented to our hospital complaining of right abdomen and groin pain for several months. On physical exam, the patient had normal genital and rectal exams. An abdominal-pelvic computed tomography (CT) scan of his abdomen and pelvis revealed a large retroperitoneal mass with radiographic characteristics of a sarcoma. Given his groin pain, the patient had a testicular ultrasound, which revealed scar tissue in the right testicle. His testicular tumor markers showed elevated β-human chorionic gonadotropin (β-hCG) and lactate dehydrogenase (LDH) but normal α-fetoprotein (AFP). He underwent right radical inguinal orchiectomy, with pathologic examination of the testicle revealing a burned-out testicular tumor. The patient was then treated with four cycles of bleomycin, etoposide, and cisplatin (BEP). His post-treatment tumor markers were normalized; however, his abdomen-pelvic CT scan showed a persistent mass. The patient underwent retroperitoneal lymph node dissection (RPLND) with the removal of 12 lymph nodes. However, pathologic evaluation of the lymph nodes revealed no evidence of neoplastic cells. The patient has remained disease-free after five years of follow-up. This report highlights the potential of burned-out testicular tumors in young and middle-aged men presenting with a retroperitoneal mass. Furthermore, it underscores the importance of obtaining testicular ultrasound in these patients to rule out regressed testicular tumors.

Histiocytic sarcoma (HS) is a rare, aggressive non-Langerhans histiocytic cell neoplasm of hematopoietic origin. Histiocytic sarcoma is prone to early systemic metastasis, rendering early diagnosis and treatment critical determinants for patient outcome. Primary HS originating from the central nervous system (CNS) is exceptionally rare and portends a poor prognosis. This grim clinical course is further complicated by the challenging diagnosis and the lack of standard treatment guidelines for the disease. This is due to the exceptionally rare nature of primary CNS histiocytic sarcoma and the limited data available on the successful management of the disease, prompting the therapeutic approach to be guided by retrospective data from case reports or single-institutional studies with a limited number of patients. Here, we report a case of a young Middle Eastern male who was diagnosed with primary CNS histiocytic sarcoma, successfully treated with frontotemporal craniotomy and adjuvant radiation therapy. We also elucidate the role of the CD163 biomarker in diagnosing HS and using surgery and adjuvant radiotherapy (RT) as a successful treatment approach for primary CNS histiocytic sarcoma.

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine cancer that primarily affects the elderly, Caucasians, and the immunocompromised. We present a rare case of an immunocompetent young Iranian (non-Caucasian) female with a small nodule on her left arm. The lesion was initially misdiagnosed as an infected cyst and was treated with antibiotics for 20 days before being surgically removed. Unfortunately, the lump regrew rapidly 2 weeks later, when she had a biopsy, which revealed stage III MCC. She was then treated with adjuvant chemoradiotherapy after a thorough surgical resection of the tumor. Despite the fact that she was in remission after completing chemotherapy courses, she developed neutropenic fever, sepsis and died from septic shock. This case emphasizes the necessity of early clinical diagnosis of MCC and obtaining a biopsy with histopathologic evaluation of rapidly evolving skin lesions suggestive of malignancy.

Testicular germ cell tumors are the most common malignancy in young and middle-aged men. Spontaneous primary testicular tumor regression, or testicular tumor burn-out, is a rare clinical phenomenon where extragonadal metastatic lesions are observed concurrently with the spontaneous regression of the primary testicular germ cell tumors. Here, we describe the case of a 36-year-old male who presented to our hospital with left-sided abdominal pain and testicular swelling and was found to have significant retroperitoneal lymphadenopathy on his abdominopelvic CT scan. His testicular ultrasound showed multiple echogenic calcifications through the right testicle consistent with microlithiasis. Biopsy of the retroperitoneal lesion revealed a mixed germ cell tumor of testicular origin composed of embryonal carcinoma and teratoma. The patient received four cycles of bleomycin, etoposide, and cisplatin, followed by retroperitoneal lymph node dissection (RPLND) and radical right testicular orchiectomy. Here, we report the second case of burned-out testicular tumor in a patient with ipsilateral cryptorchidism. Furthermore, we elucidate the etiology, clinical presentation, and diagnostic modalities in burned-out testicular germ cell tumors.