Location of injected polymethylmethacrylate microspheres influences the onset of late adverse effects: an experimental and histopathologic study

Figures & data

Figure 1 Techniques for subcutaneous and submucosal PMMA injection.

Notes: (A) Technique for subcutaneous injection: PMMA was injected in the infraorbital region. The needle was introduced subcutaneously using the tunneling technique. (B) Technique for submucosal injection: PMMA was injected submucosally via extra-oral access. The needle was introduced through the skin, crossed the muscle fibers, and the material was deposited in the submucosal tissue.
Abbreviation: PMMA, polymethylmethacrylate.

Table 1 Grading scale for inflammatory response

Grade	Histopathologic aspects
0	Lack of material
1	≤10% inflammatory cells and formation of connective tissue septa within PMMA spheres
2	10%–50% inflammatory cells and formation of collagen fibers within PMMA spheres
3	≥ 50% inflammatory cells and formation of collagen fibers within PMMA spheres
4	Granulation tissue with foreign-body reaction or encapsulation of PMMA spheres

Note: Data from Duranti et al.²⁶

Abbreviation: PMMA, polymethylmethacrylate.

Table 2 Clinical evaluation of local inflammatory response according to PMMA injection site (n=22)

Anatomic site	Clinical score		Extra-oral enlargement (n)	Pus drainage (n)	Weight loss (n)	Behavior change (n)
Subcutaneous	Early (0–14 days)	Absent	22	22	22	22
	Early (0–14 days)	Present	0	0	0	0
	Late (3 months)	Absent	22	22	22	22
	Late (3 months)	Present	0	0	0	0
Submucosal	Early (0–14 days)	Absent	22	22	22	22
	Early (0–14 days)	Present	0	0	0	0
	Late (3 months)	Absent	18	22	22	22
	Late (3 months)	Present	4	0	0	0

Abbreviation: PMMA, polymethylmethacrylate.

Figure 2 Microscopic appearance after 3 months: few inflammatory cells and formation of connective tissue septa within PMMA spheres.

Notes: Microscopic appearance 3 months after PMMA injection in the subcutaneous group showing few inflammatory cells and formation of connective tissue septa (black arrow) within PMMA spheres characterizing degree 1 of inflammation (hematoxylin-eosin, 200× magnification).
Abbreviation: PMMA, polymethylmethacrylate.

Figure 3 Microscopic appearance 3 months after PMMA injection in the submucosal group.

Notes: (A) Nodule formation with a capsule of connective tissue and mononuclear inflammatory infiltrate (black arrow) involving PMMA microspheres, characterizing degree 4 of inflammation (hematoxylin-eosin, 200× magnification). (B) Greater detail of the region demarcated by the square in the image (A) showing the presence of multinucleated giant cells (red arrows) on the surface of PMMA microspheres (hematoxylin-eosin, 400× magnification).
Abbreviation: PMMA, polymethylmethacrylate.

Figure 4 Microscopic appearance of PMMA injection in submucosal group 3 months after PMMA injection, (hematoxylin-eosin, in minor magnification).

Abbreviation: PMMA, polymethylmethacrylate.

Table 3 Histopathologic evaluation of local inflammatory response according to PMMA injection site

Anatomic site	Inflammatory response
	Grade 0	Grade 1	Grade 2	Grade 3	Grade 4	Total
Subcutaneous (n)	0	17	5	0	0	22
Submucosal (n)	1	9	8	0	4	22

Abbreviation: PMMA, polymethylmethacrylate.

Table 4 Comparative analysis of local inflammatory response to PMMA according to injection site

Anatomic site	n	Mean	SD	P-value
Subcutaneous	22	1.23	0.43	0.0009
Submucosal	22	1.86	1.17	0.0009

Note: Multiple comparisons of proportions using permutation resampling method (P<0.05).

Abbreviations: PMMA, polymethylmethacrylate; SD, standard deviation.

DurantiFSaltiGBovaniBCalandraMRosatiMLInjectable hyaluronic acid gel for soft tissue augmentation. A clinical and histological studyDermatol Surg199824131713259865196

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