Clinical Cases
Starry Spleen

Starry Spleen

The term starry spleen refers to the appearance of a spleen on CT scan when diffuse, punctate calcifications are present. The differential diagnosis for splenic calcifications is vast, but luckily the nature of the calcifications and other CT findings are helpful in discerning between many of the diagnoses.

The spleen's major functions are related to blood filtration and monitoring of erythrocyte and leukocyte function. Therefore, diseases affecting red blood cells or monocytes and hematogenously spread infections can have affects on splenic size, appearance, and function.

Differential Diagnoses for Different Presentations of Splenic Calcification



Patient with histoplasmosis showing the classic starry spleen, as well as
two calcified mesenteric lymph nodes (shown by red arrows).
Published with permission from LearningRadiology.com

The movie file below is the CT scan of cadaver 33487. Take a look at the spleen (time= 75, N11). Notice the appearance of the spleen, and the pattern of calcifications. Look now at the abdomen from time= 75-80. Notice how multiple mesenteric lymph nodes are calcified. This presentation of splenic and mesenteric lymph node calcification is most characteristic of Histoplasma capsulatum infection (Histoplasmosis).

Histoplasmosis

Histoplasma capsulatum is a fungus that is endemic to the Ohio River Valley. People living in endemic areas are commonly infected with this fungus, but less than 5% develop any symptoms. Elderly and immunocompromised patients are much more prone to developing a symptomatic Histoplasma infection. The course of Histoplasmosis is very similar to that of TB. Fungal spores from a Histoplasma mold are inhaled into the lungs. These spores then develop into the yeast form of Histoplasma, which enters the bronchial lymph nodes and spreads through the body hematogenously. These yeast cells can then be deposited in the spleen, where they are attacked by monocytes and giant cells, eventually forming a granuloma. This granuloma undergoes dystrophic calcification, which is what shows up in the spleen on CT scan.