Multifocal Desmoid-Type Fibromatosis: Case Series and Potential Relationship to Neuronal Spread

Abstract

Multifocal desmoid-type fibromatosis (DTF) is very rare and usually regional. We report three cases that initially appeared to be multifocal, but subsequent detailed imaging revealed unsuspected tracking along nerves in two cases. This neural spread is reminiscent of neuromuscular choristoma (NMC), a rare developmental lesion in which mature skeletal muscle cells, or rarely smooth muscle cells, infiltrate and enlarge peripheral nerves. NMC is frequently associated with DTF. These two cases suggest that DTF spread along nerves and appeared as distinct multifocal lesions while actually being contiguous. The third case was felt to represent true multifocal tumor development, possibly due to tumor seeding at the time of chest surgery. The relationship of DTF to NMC is discussed.

Keywords: aggressive fibromatosis; beta-catenin; ctnnb1; desmoid tumor; msh6; neuromuscular choristoma; oncology; orthopedic oncology.

Figure 1. Deep DTF

Vaginal mass biopsy from Case 1 showing myxoid and collagenous stroma containing low-grade spindle cells and slit-like blood vessels with perivascular edema (arrows) (H&E ×100) (A). Right thigh biopsy from Case 2 with keloidal-type collagen (right) in addition to spindle cell fascicles (H&E ×100) (B). Left chest wall biopsy from Case 3 (C-F) showing typical features of DTF with sweeping fascicles of spindle cells and interspersed compressed blood vessels (H&E ×40) (C). Higher magnification demonstrating spindled myofibroblasts with oval nuclei, multiple small nucleoli, and amphophilic cytoplasm in a collagenous background with extravasated red blood cells (left) (H&E ×400) (D). Beta-catenin immunohistochemical stain diffusely highlighting the lesional cells in a cytoplasmic pattern with scattered nuclear reactivity (arrows), typical of DTF (IHC ×200) (E). Immunohistochemical stain for smooth muscle actin with positive staining, confirming the myofibroblastic nature of the tumor cells (IHC ×200) (F) DTF: desmoid-type fibromatosis; IHC: immunohistochemistry; H&E: hematoxylin and eosin

Figure 2. Sequential axial MR images of Case 1

Left column (A, B): T1 sequence; middle column (C, D): T1 fat saturation sequence post contrast; right column (E, F): T2 fat saturation sequence. Black arrows indicate sciatic nerve; white arrows indicate tumor

Figure 3. Sequential axial MR images of Case 1, continuation from Figure 2

Left column (A, B): T1 sequence; middle column (C, D): T1 fat saturation sequence post contrast; right column (E, F): T2 fat saturation sequence. Black arrows indicate sciatic nerve; white arrows indicate tumor

Figure 4. Sequential axial MR images of Case 2

Left column (A-C): T1 sequence; middle column (D-F): T1 fat saturation sequence post contrast; right column (G-I): T2 fat saturation. Black arrows indicate nerves: in the top row, the femoral cutaneous nerve (A, D, G) and in the second (B, E, H) and third rows (C, F, I), the femoral nerve

Figure 5. Sequential axial MR images of Case 2, continuation from Figure 4

Left column (A-C): T1 sequence; middle column (D-F): T1 fat saturation sequence post contrast; right column (G-I): T2 fat saturation. Black arrows indicate the saphenous nerve

Figure 6. DTF resected from the left neck of Case 3

Deep DTF (left) resected from the left neck of Case 3, infiltrating the adipose tissue and in close association with large nerve bundles (arrows) (H&E ×40) DTF: desmoid-type fibromatosis; H&E: hematoxylin and eosin

Figure 7. Axial MR images of Case 3

Axial MR images of Case 3. Top row (A, D, G): neck lesion; middle row (B, E, H): chest wall lesion; bottom row (C, F, I), subscapularis lesion. Left column (A-C): T1 sequence; middle column (D-F): T1 fat saturation sequence, post contrast; right column (G-H): STIR sequence. Arrows indicate tumor STIR: short tau inversion recovery