Fig.1 
Fig. 2.
By CT scan, this 28-year-old woman was confirmed to have a large,
solid mass involving the right adrenal gland. In order to clarify
what was thought clinically to be a primary adrenal tumor, a fine-needle
aspirate and a needle core biopsy of the mass were performed.
The needle core biopsy consisted of five pieces of gray-tan tissue ranging from 0.2 x 0.1 cm to 1.8 x 0.1 cm. Smears (Figure 1) and a cell block (Figure 2) prepared from the aspirate were reported as positive for malignant cells. These showed interlacing bundles of spindle cells with cytologic abnormalities, mitotic activity and cellular degeneration. Electron microscopy done concurrently on the quite adequate fragments of tumor tissue showed that the spindle cells had the typical features of well differentiated smooth muscle cells. These consisted of fairly evenly spaced tumor cells with a mosaic-like distribution and filament accumulations in the cytoplasm (Figure 3 to 5), a rather corrugated appearance to the nuclear profiles (Figure 4) likely due to the contractility of the cytoplasmic filaments, and considerable portions of the cytoplasm occupied by myofilaments among which were many elongated, darkly staining inclusions (Figures 4 and 5).
To access light micrographs, use Figure 1.
Fig.1 Fig. 2. 
Fig.3 
Fig. 4 
Fig. 5This case illustrates the value of electron microscopy in defining spindle cell sarcomas and sarcomatoid epithelial neoplasms and how, as in this young patient, this can altered clinical management.
The differential diagnosis of spindle cell tumors in the region of the adrenal gland includes pheochromocytoma, adrenal cortical tumors, invasive or metastatic renal cell carcinoma, mesenchymal tumors of the retroperitoneum and various types of metastatic neoplasms such as malignant melanoma. Features of fine-needle aspiration biopsy (FNAB) of the rare occurrence of a spindle cell variant of adrenal cortical carcinoma have been reported [1]. The commoner situation for a primary spindle cell tumor of the adrenal is pheochromocytoma [2,3]. Primary smooth muscle tumor of the adrenal has also been reported [4], but the more usual circumstance is an adjacent leiomyosarcoma either primary of the retroperitoneum or metastatic to that site. A metastatic desmoplastic malignant melanoma involving the adrenal has also been diagnosed by FNAB [1].
Although a battery of immunohistochemical stains can assist in the differential diagnosis of spindle cell lesions of the type associated with this case, electron microscopy of such a sample can often solve the diagnostic problem more rapidly and perhaps when the diagnostic possibilities are as extensive as in this patient more cheaply. Electron microscopy is particularly suited to diagnosing sarcomas [5,6]. As this case illustrates, a leiomyosarcoma in a 28-year-old patient would not have been a prime consideration. The ultrastructural features were typical, however, for smooth muscle cells [7]. In spindle cell mesenchymal neoplasms, regardless of the site, electron microscopy can also effectively differentiate between the main considerations such as fibrosarcoma, malignant fibrous histocytoma, liposarcoma, rhabdomyosarcoma, smooth muscle tumors, and peripheral nerve sheath tumors [7,8].
Smooth muscle tumor (leiomyosarcoma) - Possibly of adrenal or retroperitoneal origin.
![[-------------------------------]](../../Images/bl_bar.gif)
