Clinicopathologic Study of Calcifying Fibrous Tumor Emphasizing Different Anatomical Distribution and Favorable Prognosis

Abstract

Aims: Calcifying fibrous tumor (CFT) is a very rare begin fibroblastic tumor featuring a widely anatomical distribution and may mimic various spindle cell tumors. Misdiagnosis and hence mistreatment are likely caused due to unfamiliarity to clinicians or junior pathologists. We collected a relatively large series of CFTs in our institution aiming at further summarizing their clinicopathologic features in Chinese patients and discussing the diagnosis and differential diagnosis in clinical practice.

Methods: Clinicopathologic data of 22 CFTs were retrospectively reviewed. Histologic features were reevaluated and summarized. Immunostaining markers include CD34, SMA, Desmin, keratin, S100, ALK1, CD117, IgG, IgG4, and Ki-67. Follow-up of all cases was performed.

Results: 22 CFTs include gastric (n=8), pulmonary (n=2), hepatic (n=2), cervical (n=1), appendiceal (n=1), esophageal (n=1), retroperitoneal (n=1), intra-abdominal (n=1), diaphragmatic (n=1), spermatic cord and scrotum (n=1), anconeal (n=1), mesenteric (n=1), and omental (n=1) lesions. Coexisting hepatocellular carcinoma, pancreatic carcinoma, pheochromocytoma, Castleman disease, and leiomyoma of the uterus and other metabolic or functional disorders were also appreciated. CFT histologically features spindle cells embedded dense hyalinized stroma with scattered psammomatous calcifications and lymphoplasmacytic infiltration and immunohistochemically for CD34. None of any individuals die of CFT per se.

Conclusion: Our study discloses that CFT is a bona fide benign fibroblastic lesion, regardless of its developing location. Involvement of digestive tract seems much more common in the Chinese population. Awareness of the clinicopathologic characteristics of this rare entity and its mimickers contribute to avoiding misdiagnosis and mistreatment in clinical practice.

Figure 1

Imaging characteristics of CFT. Axial CT scan showed a soft-tissue density nodule (arrow) with centrally prominent calcification on the gastric wall (case 16) (a); meanwhile, the contrast-enhanced CT indicated two hepatic masses with mild enhancement (arrow; case 16) (b); the coronal CT scan demonstrated a round mass (arrow) with evident calcification in the upper-left abdominal cavity (case 19) (c); axial CT revealed a mass with calcification in the abdominal cavity in proximity to the tail of the pancreas (arrow; case 19) (d); contrast-enhanced CT indicated the well-defined mass mild enhancement peripherally (arrow; case 19) (e); gastroscopy showed a submucosal bulging mass (arrow) with overlying intact smooth mucosa (f).

Figure 2

Histologic features of CFT. Spindle cells are embedded in the hyalinized stroma with prominent chronic inflammation and calcification (a; ×100); moderate power shows psammomatous calcification (arrowhead) and abundant plasma cells; Russell's bodies either inside or outside of plasmacytes are frequently appreciable (arrow) (b, ×200); prominent hyalinized stroma results in the paucity of tumor cells and lymphoplasmacytic reaction; note the well-circumscribed border and compressed lung tissues in the lower side of this figure (c; ×50); dystrophic calcification is not uncommon (d; ×200); CFT involves liver; note the well-defined border against the normal hepatic tissue (left side) and the coexisting moderate to low differentiated hepatic carcinoma in other region (inset) (e; ×100); CFT juxtaposes Castleman's disease (lower side) characterized by increased regressed lymphoid follicles and scattered tiny calcifications (f; ×100).

Figure 3

Immunohistochemical features of CFT. The spindle cells express CD34 (a; ×200); proliferative index Ki-67 is typically low (b, ×200); CD38 highlight the abundant plasma cells (c, ×200).