Invasive histiocytoma in the ear canal of a dog.

BACKGROUND: Cutaneous histiocytomas (CH) are derived from epidermal Langerhans cells. Single CH are generally associated with a good prognosis in dogs because most undergo spontaneous remission. However, aggressive behaviour and lymph node metastasis have been reported in a small number of dogs with single CH. OBJECTIVE: To describe the clinical presentation, treatment and disease progression of an aggressive CH located in the ear canal of a dog. ANIMAL: An 8-year-old intact male Rottweiler dog. METHODS AND MATERIALS: A unilateral ear canal mass was identified as a CH on routine haematoxylin and eosin stained samples. The diagnosis was confirmed by the demonstration of markers associated with Langerhans cells (Iba-1, E-cadherin and CD18) and the absence of markers associated with B cells (CD79a, CD20, Pax5), T cells (CD3), plasma cells (Mum-1) and macrophages (CD11d, CD204). RESULTS: A total ear canal ablation was performed, but tumour cells extended throughout the horizontal canal and to the deep surgical margin. Due to the locally invasive nature of the mass and incomplete excision, adjunctive chemotherapy with CCNU was pursued. No measurable local disease was appreciable at the time of the last treatment. At 250 days post-surgery the dog was euthanized owing to the development of multiple abdominal masses. No evidence of local tumour recurrence was noted. CONCLUSIONS AND CLINICAL IMPORTANCE: Although single CH are typically associated with benign behaviour, the mass in this dog demonstrated locally invasive behaviour. Cutaneous histiocytomas in the ear canals of dogs may represent a particularly aggressive variant of the condition.

Prostate-Specific Membrane Antigen-Negative Metastases-A Potential Pitfall in Prostate-Specific Membrane Antigen PET.

Ga-PSMA-11 PET/CT was performed in a 74-year-old man because of biochemical recurrence of prostate cancer following radiation therapy of the prostate gland 24 months earlier. Besides focal nuclide accumulation in the prostate gland suggestive of local recurrence, PET scan revealed no further pathologic uptake. However, CT showed multiple pulmonic nodules suggestive of metastases. Thoracotomy and pathologic examination revealed the nodules to be prostate cancer metastasis. Furthermore, immunohistochemical staining with PSMA antibodies demonstrated a virtual lack of PSMA expression. This case demonstrates the possibility of PSMA-negative metastases of prostate cancer an important pitfall that should be known to physicians interpreting PSMA PET.

Unusual Malignant Solid Neoplasms of the Kidney: Cross-Sectional Imaging Findings.

Malignant kidney neoplasms are the most frequently encountered solid kidney masses. Although renal cell carcinoma is the major renal malignancy, other solid malignant renal masses should be considered in the differential diagnosis of solid renal masses that do not contain a macroscopic fatty component. In this pictorial essay, we present the imaging findings of a primitive neuroectodermal tumor, primary liposarcoma of the kidney, primary neuroendocrine tumor, leiomyosarcoma, synovial sarcoma, malignant fibrous histiocytoma, sclerosing fibrosarcoma and renal metastasis of osteosarcoma.

Unusual Malignant Solid Neoplasms of the Kidney: Cross-Sectional Imaging Findings

Malignant kidney neoplasms are the most frequently encountered solid kidney masses. Although renal cell carcinoma is the major renal malignancy, other solid malignant renal masses should be considered in the differential diagnosis of solid renal masses that do not contain a macroscopic fatty component. In this pictorial essay, we present the imaging findings of a primitive neuroectodermal tumor, primary liposarcoma of the kidney, primary neuroendocrine tumor, leiomyosarcoma, synovial sarcoma, malignant fibrous histiocytoma, sclerosing fibrosarcoma and renal metastasis of osteosarcoma.

Pulmonary crystal-storing histiocytoma in a patient without a lymphoproliferative disorder.

Pulmonary crystal-storing histiocytoma is a very rare disorder and is characterized by infiltration of histiocytes with intracytoplasmic accumulation of crystallized immunoglobulins. It is usually associated with lymphoproliferative diseases or plasma cell dyscrasia. Here, we report a case of pulmonary crystal-storing histiocytoma in a 64-year-old man, presenting as a chronic pulmonary consolidation in the lung exposed to asbestos. Video-assisted thoracoscopic surgical biopsy displayed sheets of large, epithelioid histiocytes filled with a large number of needle-like crystals, showing the accumulation of crystallized polyclonal immunoglobulins. This lesion was consistent with crystal-storing histiocytosis or crystal-storing histiocytoma. With extensive clinical work-up, the current case was not associated with lymphoproliferative diseases. Herein, we present this extremely rare entity of pulmonary pathology, a pulmonary crystal-storing histiocytoma arising in the lung exposed to asbestos, and demonstrate the clinical, radiologic, and pathologic features of the tumor.