Fibrofolliculoma with ancient/pseudosarcomatous features

Spindle Cell/Pleomorphic Lipoma With Trichodiscoma-like Epithelial Hyperplasia Mimicking Atypical Fibroxanthoma/Pleomorphic Dermal Sarcoma

ABSTRACT

A 58-year-old man presented with a lesion on the nose suspicious for basal cell carcinoma. An initial biopsy specimen reviewed at an outside institution showed a cytologically atypical spindle cell proliferation that lacked expression of cytokeratins or melanocytic markers. The resulting differential diagnosis included atypical fibroxanthoma and pleomorphic dermal sarcoma. Histopathologic examination of the excision specimen at our institution revealed an intradermal pleomorphic and spindle cell tumor which extended into underlying skeletal muscle. The tumor was associated with a fibromyxoid stroma, scattered adipocytes, and hyperplastic folliculosebaceous epithelium at the periphery. The pleomorphic tumor cells showed hyperchromatic nuclei with smudgy chromatin, and no mitotic activity was detected. Overall, the cellularity was less than would be expected for atypical fibroxanthoma/pleomorphic dermal sarcoma. Furthermore, the tumor cells were strongly positive for CD34 and showed diffuse loss of retinoblastoma protein by immunohistochemistry. Consequently, a diagnosis of benign CD34-positive pleomorphic spindle cell tumor was rendered, with features overlapping between spindle cell/pleomorphic lipoma and trichodiscoma. Subsequent single-nucleotide pleomorphism array testing revealed heterozygous loss of chromosome 13q in a region that spanned the RB1 locus and copy number loss at 16q, favoring that the proliferation in fact represents a spindle cell/pleomorphic lipoma with trichodiscoma-like epithelial induction. This case highlights an important diagnostic pitfall that may be avoided by recognizing characteristic architectural and cytologic features of this spectrum of lesions.

Case report of a solitary fibrofolliculoma on the alar rim

Fibrofolliculoma is a benign tumor characterized by a smooth, dome-shaped papule of size 2–4 mm. Most fibrofolliculomas occur as multiple lesions, and very rarely, they are solitary. Herein, we report a case of solitary fibrofolliculoma found in the alar rim, without the typical characteristics of a fibrofolliculoma. A 42-year-old man visited the hospital with a protruding lesion that had occurred 1 year previously. A mass of size 5× 7 mm was observed on the left alar rim. The tumor was dome-shaped and palpable. The patient did not have any similar lesions elsewhere. No family member was known to have such a lesion. An incisional biopsy was performed before surgery, and pathological examination revealed hyperkeratosis and dyskeratosis; however, an accurate diagnosis was not made. Complete resection was planned for the mass on the alar rim. The resected mass was subjected to permanent biopsy, and the pathological examination results led to the diagnosis of fibrofolliculoma. Therefore, when diagnosing a dome-shaped mass in the alar rim, despite the suspicion of a very rare disease, it is necessary to suspect fibrofolliculoma and consider the process from diagnostic examination to treatment.

Solitary fibrofolliculoma of the upper eyelid in a 68-year old female: a case report

BACKGROUND

Fibrofolliculoma is a benign, perifollicular, connective tissue tumor, and it usually arises in the form of multiple lesions, but rarely as a solitary lesion. We report a case of solitary fibrofolliculoma on the eyelid.

CASE PRESENTATION

A 68-year-old female presented with an asymptomatic mass on the right upper eyelid. The lesion appeared as a flesh-colored, dome-shaped, smooth nodule being the size of 5 × 5 × 4 mm, with eyelashes protruding from the surface, and located on the upper lid margin. Shave excision was performed, and the diagnosis of fibrofolliculoma was confirmed finally through histological exam.

CONCLUSIONS

Solitary fibrofolliculomas rarely arises on the eyelid. However, it should be suspected when a flesh-colored and doom-shaped lesion of the eyelid is encountered. The benign tumor on the lid margin can be removed by shave biopsy.

Spindle Cell Predominant Trichodiscoma or Spindle Cell Lipoma With Adnexal Induction? A Study of 25 Cases, Revealing a Subset of Cases With RB1 Heterozygous Deletion in the Spindle Cell Stroma

In our routine and consultative pathology practices, we have noticed that a relatively high proportion of spindle cell predominant trichodiscomas demonstrate a remarkable stromal admixture of adipose tissue, which along with spindle cells, prominent collagen bundles and myxoid change closely resembles spindle cell lipoma (SCL). To clarify their possible relationship to SCL, 25 cases of trichodiscoma and fibrofolliculoma with stromal "lipomatous metaplasia" were collected and examined using immunohistochemical stains [CD34 and retinoblastoma-1 (RB1) protein] and fluorescence in situ hybridization (RB1 deletion). The patients ranged in age from 35 to 81 years (median 64 years). The male to female ratio was almost equal (14:11). All tumors with a known location were situated on the face with a special predilection for the nose. All cases were sporadic, with all patients having a single lesion and showing no clinical features of Birt-Hogg-Dubé syndrome. No case with available follow-up presented with a recurrence or an otherwise aggressive clinical course. Spindle cell stroma was immunohistochemically positive for CD34 in 16 of 20 cases, and 18 of 19 cases showed loss of RB1 staining in lesional spindle cells. Fluorescence in situ hybridization analysis detected RB1 gene heterozygous deletion in 6 of 20 cases. We conclude that despite the SCL-like appearance of the investigated cases, the majority of them supposedly represent genuine spindle cell predominant trichodiscomas with adipose tissue admixture. However, there was a subset of histopathologically indistinguishable cases with proved RB1 deletion, which likely represent SCL with trichodiscoma/fibrofolliculoma-like epithelial/adnexal induction rather than spindle cell predominant variant of trichodiscoma.

Symplastic trichodiscoma: a spindle-cell predominant variant of trichodiscoma with pseudosarcomatous/ancient features

Trichodiscomas are hamartomatous lesions of the follicular unit and of its surrounding stroma composed of epithelial and mesenchymal tissue elements. The dominating tissue element in trichodiscoma is the central fibrous stroma, encircled by prominent clusters of sebaceous lobules that resemble mitts. Rare variants of trichodiscomas with CD34-positive spindle cell-pedominant stroma have been described. We report a case of spindle cell-predominant trichodiscoma with prominent pseudosarcomatous/ancient features consisting in numerous large atypical spindle cells with frequent multinucleation, with no mitotic activity. The cytological changes were similar to those described in ancient schwannoma and symplastic hemangioma. We propose to call this lesion symplastic trichodiscoma. Only 1 previous case of fibrofolliculoma with pseudosarcomatous/ancient changes has already been reported. Although such lesions can appear worrisome at first glance, their benign evolution, the absence of mitosis, and the phenotypic studies excluding malignant differential diagnoses like atypical fibroxanthoma are reassuring. The precise pathogenesis of the symplastic features in schwannoma as in trichodiscoma/fibrofolliculoma is not known yet.