Histologic Changes

When cellular, non-necrotic granulomas are present in tuberculosis, the epithelioid cells and giant cells sometimes have inclusions, which were found in this case. These inclusions, the Schaumann body and the asteroid body, are not specific for tuberculosis. They also occur in most other types of non-necrotic granulomas.

Schaumann Bodies (SB): SBs are basophilic, lamellated, shell-like (conchoidal) bodies found in the cytoplasm of multinucleated giant cells of granulomas. Large SBs may be found extracellularly, as well. In addition, there is often a crystalline component that sometimes occurs alone.

Crystalline component of SB

In our case, only the crystalline component of the SB was found. Crystals were present only in non-necrotizing granulomas. They are easily missed (left panel) if the section is not viewed with polarized light (right panel).

Lamellated component of SB

An extracellular SB from another case shows a basophilic, lamellated, conchoidal structure (arrows) surrounded by several multinucleated giant cells. Epithelioid cells are located in the lower half of the granuloma, and lymphocytes are scattered throughout.

Incidence: SBs are most frequent in sarcoidosis (88% of 17 cases), less frequent in beryllium disease (62% of 52 cases), and least frequent in active tuberculosis (6% of 100 cases). In tuberculosis, they are found in non-necrotizing granulomas and not in areas of caseation. SBs have also been noted in granulomas of Crohn's disease, hypersensitivity pneumonia, histoplasmosis, and lymph nodes draining cancer [1-3].

Structure of conchoidal component: The basophilic component of the SB varies from 25 to 200 µm in diameter [3]. Elemental analysis of the SB indicates the presence of calcium, phosphorus, and iron. In an electron microscopic study of early SBs, it appeared that the mineral salts were deposited on lamellated, phospholipid, myelin figures that develop in the cytoplasm of multinucleated giant cells [4].

Nature of crystalline component: The crystals are colorless and brightly birefringent. They occur singly or in clumps. Size varies from 1-20 µm in diameter. Analysis suggests that they are composed of calcium oxalate. The crystals are soluble in water or formalin and tend to dissolve as the fixation time increases. When crystals occur alone, they should not be mistaken for foreign material such as talc or silica [2].

References:

1. Williams W. The nature and origin of Schaumann bodies. J Path Bact 1960; 79:193-201.

2. Reid J, Andersen M. Calcium oxalate in sarcoid granulomas. With particular reference to the small ovoid body and a note on the finding of dolomite. Am J Clin Pathol 1988; 90:545-558.

3. Rosen Y, Vuletin J, Pertschuk L, Silverstein E. Sarcoidosis from the pathologist's vantage point. Pathol Annu 1979 Part 1; 14:405-439.

4. Kirkpatrick C, Curry A, Bisset D. Light- and electron-microscopic studies on multinucleated giant cells in sarcoid granuloma: new aspects of asteroid and Schaumann bodies. Ultrastruct Pathol 1988; 12:581-597.

Clinical summary Image 3

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