Solitary fibrous tumor is a soft tissue neoplasm initially described in the pleura but subsequently reported in a wide variety of locations. The clinical behavior is usually benign, but the existence of aggressive cases has been documented both in the pleura and in extrapleural sites. In this report clinical and pathologic features of seven solitary fibrous tumors of the thyroid gland are presented. Patients' ages ranged from 43 to 64 years (mean 52 years), and tumor sizes varied from 2 to 6 cm. Grossly, the tumors were white-tan and well circumscribed. Microscopically, there was a variegated, wavy, storiform, hemangiopericytic or desmoid-like arrangement of spindle cells. Trapped thyroid follicles within the tumor and peripheral jagged tumor infiltration among follicles were common. There was immunohistochemical reactivity for CD34, CD99, and bcl-2, and ultrastructural analysis of one tumor was consistent with a fibroblastic lineage. The differential diagnosis included other benign and malignant mesenchymal tumors of the thyroid, spindle cell follicular adenoma, Riedel's thyroiditis, the spindle cell, and paucicellular variants of anaplastic carcinoma, papillary thyroid carcinoma with exuberant nodular fasciitis-like stroma, and the spindle epithelial tumor with thymus-like differentiation. The cumulative data of 13 cases (comprised of the seven present cases and the six previously reported) suggest a benign clinical behavior for thyroid SFT.

We are reporting a peculiar variant of penile squamous cell carcinoma (SCC) characterized by its peculiar deeply penetrating and burrowing pattern of growth. This low grade, verruciform penile neoplasm is similar to the plantar epithelioma cuniculatum originally described by Ayrd in 1954. Clinical and pathologic features of 7 patients are presented. There were 7 partial penectomies and 4 bilateral inguinal node dissections. The mean patient's age was 77 years. Grossly, the tumors were white to gray, exo-endophytic, and papillomatous with a cobblestone or spiky appearance. All cases affected the glans and extended to coronal sulcus and foreskin (average size was 6.3 cm). The hallmark of the lesion was noted on cut surface where there were deep tumoral invaginations forming irregular, narrow, and elongated neoplastic sinus tracts connecting the surface of the neoplasm to deep anatomic structures. The neoplasm invaded through lamina propria and corpus spongiosum and grew along the loose connective tissue of Buck fascia to involve the tunica albuginea and corpora cavernosa (average depth was 32 mm). Deeply invasive keratin filled cysts or crypts, on serial sections, showed to be connected to the surface tumor. Fistulization to the skin was also noted. Microscopically, the lesions corresponded to well-differentiated carcinomas with bulbous front of invasion. There were focal areas of higher histologic grade and more infiltrative and jagged borders in 4 cases. Inguinal nodes were negative in 4 patients in which groin dissection was performed. Carcinoma cuniculatum is a variant of penile SCC with distinctive growth pattern and should be distinguished from other verruciform tumors such as the verrucous, papillary, and warty carcinomas. Unlike most subtypes of penile SCCs and despite the deep invasion, none of the tumors showed groin or systemic dissemination at time of diagnosis.

The frequent coexistence of lichen sclerosus, squamous hyperplasia, differentiated PeIN and low-grade SCC suggests a common non-human papillomavirus related pathogenic pathway for preputial lesions, and highlights the importance of circumcision in symptomatic patients for the prevention of penile cancer.