Massive splenic hamartoma with bizarre stromal cells.

Abstract

well-demarcated and encapsulated mass with focal infarcts, extensive hemorrhage, and extramedullary hematopoiesis, including erythropoiesis and megakaryopoiesis (Fig. 1c). Thick bands of hypocellular fibrosis, disorganized sinusoids, and vascular spaces separated by red-pulp stroma, without any white pulp elements, were observed. Many dispersed small lymphocytes, plasma cells, siderophage, and a few siderotic nodules (Gamna–Gandy bodies) were also noted in the background. The most striking population was scattered bizarre stromal cells, which were seen throughout the stroma without any association with vascular lumina. These cells composed of round to oval distorted or multilobulated nuclei, open chromatin, conspicuous nucleoli and scant cytoplasm (Fig. 1d). Large and pale intranuclear pseudo inclusions were frequently identified. Although their morphology was worrisome, they were devoid of some features of malignancy such as hyperchromasia, increased mitosis, or infiltrative growth pattern. An immunohistochemical panel containing CD34, CD31, CD8, CD163, CD138, Kappa, Lambda, CD30, S100, nerve growth factor receptor, smooth muscle actin, Desmin, and Pancytokeratin was performed. The bizarre cells were negative for all markers except focal and faint positivity for Desmin. Immunostains confirmed vascular and sinusoidal disorganization within the lesion. Plasma cells were polytypic for Kappa and Lambda light chains. Additionally, special stains for Grocott’s methenamine silver and acidfast bacilli were negative for any microorganism. Although these cells raised suspicion of malignancy, they were completely benign in nature. Their deceptively malignant morphology and lack of specific expression of any immunohistochemical marker are attributable to degenerative changes that can result from losing connections with microenvironmental elements and deteriorated nutritional supply [1].