Fibroblastic Connective Tissue Nevus

Abstract

Fibroblastic connective tissue nevus (FCTN) represents a rare and distinct benign cutaneous mesenchymal lesion of fibroblastic/myofibroblastic lineage, which broadens the spectrum of lesions presently recognized as connective tissue nevus. A series of 25 cases of FCTN has been analyzed to further characterize the clinicopathologic spectrum and immunohistochemical features of this entity. Sixteen patients were female (64%) and 9 were male (36%), with age at presentation ranging from 1.5 months to 58 years (median, 10 y). Most patients presented with a solitary, slowly growing, painless plaque-like or nodular skin lesion. Eleven cases (44%) arose on the trunk, 9 (36%) on the head and neck, and 5 (20%) on the limbs. The lesion was present for a median duration of 11.5 months (mean, 13.2 mo). Grossly, the lesions were tan-brown to tan-white, smooth, and firm. Their size ranged from 0.3 to 2.0 cm in greatest dimension (mean size, 0.67 cm; median, 0.6 cm). All tumors showed poor circumscription and were situated primarily in the reticular deep dermis, extending into the superficial subcutis in 13 cases (52%). The lesion was associated with papillomatous epidermis in 17 cases (70%) and the presence of adipose tissue in the reticular dermis in 14 cases (60.9%). All tumors were composed of a proliferation of bland intradermal fibroblastic/myofibroblastic cells with indistinct palely eosinophilic cytoplasm and tapering nuclei, with no significant cytologic atypia or pleomorphism, arranged in short-intersecting fascicles and entrapping appendages. No mitoses were identified. Immunostains showed positivity for CD34 in 20 of 23 cases (87%) and weak focal positivity for smooth muscle actin in 9 of 19 cases (47%). No case stained positively for desmin or S100 protein. Clinical follow-up was obtained for 14 patients (median duration, 4 y). No tumor recurred locally, even when surgical excision was incomplete. No lesion metastasized. FCTN occurs most commonly as a plaque on the trunk and head/neck of children, involves deep dermis and superficial subcutis, and stains mainly for CD34. FCTN most likely represents a localized developmental dermal anomaly; it is entirely benign and should not be confused with dermatofibrosarcoma protuberans or other neoplasms such as dermatomyofibroma.

Subcutaneous mass of the forearm

“…In recent years, the list of soft tissue neoplasms with fibroblastic and myofibroblastic differentiation has continued to grow. FCTN was first described by deFeraudy and Fletcher as an uncommon, benign, cutaneous mesenchymal neoplasm of fibroblastic and myofibroblastic origin 1 . Clinically, it presents as a solitary, slow‐growing plaque or nodule on the head, neck, or trunk in children, although reports of FCTN in individuals as old as 58 years have been described 1–4 .…”

“…FCTN was first described by deFeraudy and Fletcher as an uncommon, benign, cutaneous mesenchymal neoplasm of fibroblastic and myofibroblastic origin 1 . Clinically, it presents as a solitary, slow‐growing plaque or nodule on the head, neck, or trunk in children, although reports of FCTN in individuals as old as 58 years have been described 1–4 . The literature reports a slight predilection for females, and lesion size typically ranges between 0.3 and 2.0 cm in size, although cases of FCTN measuring as large as 3 × 4 cm have been documented 1–5 …”

“…DFSP often presents with protuberant nodules arising in a plaque, whereas FCTN commonly presents as a single, smooth, firm plaque. DFSP has a propensity for recurrence, 1,2,6 while FCTN has not been reported to recur after surgical excision. Histologically, DFSP is characterized by more hyperchromatic nuclei, scattered mitoses, and characteristic extension into subcutaneous adipose tissue giving it a “Swiss cheese‐like” appearance.…”

“…1 Clinically, it presents as a solitary, slow-growing plaque or nodule on the head, neck, or trunk in children, although reports of FCTN in individuals as old as 58 years have been described. [1][2][3][4] The literature reports a slight predilection for females, and lesion size typically ranges between 0.3 and 2.0 cm in size, although cases of FCTN measuring as large as 3 9 4 cm have been documented. [1][2][3][4][5] Histological examination reveals mild epidermal hyperplasia overlying a poorly circumscribed, dermal to subcutaneous proliferation of spindle cells arranged in haphazard fascicles.…”

“…[1][2][3][4] The literature reports a slight predilection for females, and lesion size typically ranges between 0.3 and 2.0 cm in size, although cases of FCTN measuring as large as 3 9 4 cm have been documented. [1][2][3][4][5] Histological examination reveals mild epidermal hyperplasia overlying a poorly circumscribed, dermal to subcutaneous proliferation of spindle cells arranged in haphazard fascicles. Adnexal entrapment may be observed without alterations to the architecture.…”