Fig. 22.35 Proliferative myositis. (A) Firm tumor of one week's duration in the sternocleidomastoid. Aspiration resulted in a conclusive diagnosis of
proliferative myositis. (B) Same patient 10 days after initial biopsy. No palpable tumor left.
should include fibrosarcoma, malignant fibrous histiocytoma,
and schwannoma. In cases of large or deep lesions diagnosed
as nodular fasciitis, clinical control and repeat biopsy are
advisable. In extreme cases, we have monitored patients using
biopsies at 2-week intervals for 2 months before the lesion
started to regress.
Key features of nodular fasciitis
Collagen or myxoid substance;
Fibroblasts with ovoid nuclei;
Plump myofibroblasts with polyhedral or triangular
Eccentric nucleus; and
This process is an intramuscular counterpart of proliferative
fasciitis. It grows rapidly without causing significant pain. No
sex predilection is noted. Patients are often middle-aged. The
muscles of the trunk are most frequently affected. In rare cases,
the sternocleidomastoid muscle is involved (Fig. 22.35).
Surgical biopsy samples disclose a fibroblastic proliferation
in the stromal tissue. Giant cells with an eccentric nucleus,
distinct nucleoli, and a large polyhedral cytoplasm are frequent.
The muscular tissue shows atrophy without regeneration.
Smears contain fibroblast-like spindle cells and numerous
giant cells, which have a sharply outlined polygonal cytoplasm
(Fig. 22.36). Binucleate giant cells and inflammatory cells are
also present.77 In addition, muscle fibers with signs of atrophy
are a constant finding. The differential diagnostic considerations
should be the same as those for nodular fasciitis.
Fig. 22.36 Proliferative myositis. Fine-needle aspiration smear from
the patient shown in Fig. 22.35. Muscle fragment, immature fibroblasts, and
inflammatory cells are present (May-Grünwald-Giemsa x HP).
Key features of proliferative myositis
Loose fragments of spindle cells with some myxoid
Muscle fibers with signs of atrophy;
Fibroblast-like cells with ovoid nuclei; and
Giant cells, sometimes binucleated, with large
polyhedral cytoplasm ("ganglion cell").
Carotid Body Tumor
The carotid body is the origin of this tumor, which usually
appears as a firm ovoid mass in front of the sternocleidomas-
toid muscle. Bilateral tumors are extremely rare (Fig. 22.37). The
clinical presentation may vary, and the tumor can sometimes