Primary Intraosseous Adenoid Cystic Carcinoma with Widespread Skeletal Metastases Showing Features of High-Grade Transformation

Abstract

Malignant salivary gland carcinomas arising primarily within the jaw bones are extremely rare. The most common salivary malignancy in these locations is mucoepidermoid carcinoma followed by adenoid cystic carcinoma and adenocarcinoma. The clinical picture and imaging studies of these malignancies may be confused with odontogenic lesions which are more common in this location. Adenoid cystic carcinomas have a prolonged clinical course, tendency for perineural invasion and distant metastasis and multiple recurrences. The diagnosis of these tumors requires thorough histopathologic examination. Immunohistochemical studies may be required in cases showing solid growth pattern. High-grade transformation, earlier termed as dedifferentiation, has been observed in several salivary gland carcinomas including adenoid cystic carcinoma. These transformed tumors are reported to have an extremely poor prognosis. Here, we report a case of primary intraosseous adenoid cystic carcinoma with extensive skeletal metastases which showed a negative staining with p63 and positive staining with CD117. The tumor had a predominant solid growth pattern with areas indicative of high-grade transformation. A negative p63 staining may indicate an incomplete or focal loss of abluminal layer and this is one of the criteria for high-grade transformation in adenoid cystic carcinoma.

Keywords: Adenoid cystic carcinoma; Female; Head and neck neoplasms; Humans; Immunohistochemistry; Mandible; Paraesthesia; Salivary gland neoplasms.

Fig. 1

MDCT* showing the lytic expansile lesion with destruction of bony cortices involving the body of mandible on right side with soft tissue density component seen within and around the lytic lesion. *Multidetector computed tomography

Fig. 2

Histologic findings of incision biopsy showing an invasive neoplasm composed of cells arranged mainly in solid nests (×10, H&E*). *Haematoxylin & eosin

Fig. 3

Histologic picture showing arrangement of tumor cells. a Arranged in nests, cords and focal cribriform pattern (×5, H&E*). b High power of cribriform pattern (× 40, H&E*). *Haematoxylin & eosin

Fig. 4

Histologic picture showing solid islands. a Low power of solid islands showing comedonecrosis (× 10, H&E*). b High power view of one island showing predominantly round to oval cells with fine granular chromatin and scant cytoplasm(arrow) admixed with few spindle to oval cells with hyperchromatic nuclei and scant cytoplasm(arrowhead). The center of the island shows comedonecrosis (asterisk). (×40, H&E*). *Haematoxylin & eosin

Fig. 5

Histologic picture showing invasion. a Vascular invasion of tumor cells (×20, H&E*). b Invasion into the adjacent adipose tissue (×20, H&E*). *Haematoxylin & eosin

Fig. 6

Histologic picture showing special features. a Islands of clear cells (× 20, H&E*). b Micropapillary growth pattern (×20, H&E*). c Stromal desmoplasia (×5, H&E*). d Ductal pattern (×20, H&E*). *Haematoxylin & eosin

Fig. 7

Immunohistochemical staining. a Positivity with CK7. b Negative staining with p63. c Focal staining with S100. d Positive staining with CD117

Fig. 8

PET* imaging studies showing lytic lesions with increased uptake in a right temporal/sphenoid bones. b Right side of mandible. c Right ischium. d Dorsal 5 (T5) vertebrae. *Positron emission tomography