Cutaneous Adenodermatofibroma: Report of 2 Cases

Giant Hemosiderotic Adenodermatofibroma: A Case Report and Review of the Literature

ABSTRACT

Adenodermatofibromas are an extremely rare subtype of dermatofibroma (DF) characterized by a dermal proliferation of spindle-shaped fibroblasts and histocytes, dilated glandular structures with apocrine secretion, and prominent vascular proliferation, with or without hemosiderotic features. We describe a recent extraordinary case of a hemosiderotic adenodermatofibroma in a 25-year-old female. We review histologic findings and theories behind etiology, as well as review the spectrum of clinical presentations for this lesion. We also discuss imaging findings that may make identification of these entities challenging.

Two cases of adenodermatofibroma

Dermatofibromas (DF) are common skin lesions composed of a dermal proliferation of fibroblasts and histiocytes. Among the variants of DFs, adenodermatofibroma are characterized by a dense proliferation of fibroblasts and histiocytes admixed with entrapped dilated glandular structures. We report two additional cases of adenodermatofibromas, review the literature, theorize on the histopathogenesis of this variant, and suggest that there are different patterns among adenodermatofibromas, from primarily cystic to primarily glandular.

Primary cutaneous solitary fibrous tumor with entrapped eccrine components

First described in the pleura, solitary fibrous tumor (SFT) was subsequently reported in a variety of organ systems. Compared to other anatomic sites, primary cutaneous and superficial SFTs are relatively rare. Although several histopathologic variants of cutaneous and superficial SFT have been described, a primary cutaneous SFT harboring glandular components has not hitherto been documented in the literature. The current case report describes a spindle cell neoplasm of the right finger in a female patient with characteristic morphologic and immunohistochemical features of a SFT. Unexpectedly, various glandular and ductal components were identified in the SFT. A few hyperplastic lobules of sweat glands demonstrating similar morphology as the intratumoral glandular components and composed of secretory coils displaying mucinous metaplasia and ducts were detected in the attached subcutaneous tissue, suggestive of an inductive or obstructive effect of the SFT on the eccrine units. The intratumoral glands and ducts were judged to represent entrapped benign eccrine components from the attached subcutaneous tissue. Since this variant of SFT with entrapped eccrine components could mimic many biphasic epithelial and stromal tumors, pathologists should be aware of this unusual variant of SFT to avoid potential erroneous diagnosis, particularly mistaken confusion with a biphasic synovial sarcoma.

Dermatopathology of Cutaneous Cystic Lesions: A Practical Review With Diagnostic Clues and Pitfalls

BACKGROUND

Cystic lesions are common in the daily practice of dermatologists and dermatopathologists, and in most cases, a straightforward diagnosis can be done. Yet, some variants and situations may cause diagnostic problems or carry prognostic and/or systemic implications.

OBJECTIVE

To review the histopathological features of the most frequent cystic lesions, either true cysts or pseudocysts, and provide some clues and pitfalls to bear in mind for troublesome situations such as solid-cystic tumors; uncommon variants; incidental findings; artifactual, reactive, or infectious cavities; cysts as a warning of systemic and hereditary diseases; and malignant cystic tumors, either primary or metastatic.

METHODS

The histopathological diagnostic criteria of most cystic lesions and their potential caveats will be discussed, offering some diagnostic clues.

RESULTS

Cystic lesions of the skin can primarily be classified into true cysts and pseudocysts. The most frequent pseudocysts are sinus pilonidalis and mucin-filled cavities. True cysts can be divided according to their epithelial origin or differentiation into epidermal/pilar cysts, cysts from glandular appendages, and from embryonic remnants. Diagnostic dilemmas and possible pitfalls in cystic lesions are reviewed, offering some keys to solve them.

CONCLUSIONS

Knowledge of the histopathology of cystic lesions contributes to their correct diagnosis, improving the management of patients.

Perineural Invasion as a Clue to Malignant Behavior in a Dermatofibroma

Dermatofibroma (DF) represents one of the most common mesenchymal proliferations of the skin. Their recurrence rate, even when incompletely excised, is very low, whereas the atypical, aneurysmal, and cellular variants have recurrence rates of up to 20% each. Extraordinary rare malignant lesions with metastases to lymph nodes and/or lung have been described. We report a 64-year-old woman with a long history (years) of a skin lesion on her right arm that became painful during the last months. Histologically, it consisted of a conventional cellular DF in which perineural invasion was present. Subsequently, the lesion showed a clinically aggressive course with recurrences, sarcomatous transformation, and pulmonary metastases. Given that no predictive morphological features have been identified to separate classical benign DF from rare metastasizing forms, perineural invasion in an otherwise conventional DF could be a histopathologic clue for an adverse prognosis and should provoke a closer clinical follow-up.