Dome-Shaped Papule on the Posterior Shoulder—Quiz Case

Loss of retinoblastoma in pleomorphic fibroma: An immunohistochemical and genomic analysis

“…Mitotic figures and adipocytic metaplasia occur in a minority of cases. These variations are congruent with prior reports of pleomorphic fibroma and its variants …”

“…In addition to the prototypical cells with prior reports of pleomorphic fibroma and its variants. [1][2][3][4] To our knowledge, we present the first cytogenetic analysis of pleomorphic fibromas since its introduction into the diagnostic lexicon over 25 years ago. 1 Our results reveal loss of retinoblastoma protein expression in all 26 cases of pleomorphic fibroma, and a correlating loss of the RB1 gene was detected in all 7 tumors successfully assessed by aCGH.…”

“…Despite the atypical cytologic features, the proliferative index was low with rarely identified cells in mitosis and clinical follow up was benign. Additional reports demonstrate that pleomorphic fibroma may exhibit marked variability in stromal alteration, ranging from sclerotic to fibrotic to myxoid, and may pose a diagnostic challenge in some cases . In cases with exuberant sclerosis, some authors have identified immunohistochemical overlap with sclerotic fibroma (sclerotic pleomorphic fibroma) …”

“…Additional reports demonstrate that pleomorphic fibroma may exhibit marked variability in stromal alteration, ranging from sclerotic to fibrotic to myxoid, and may pose a diagnostic challenge in some cases. 2,3 In cases with exuberant sclerosis, some authors have identified immunohistochemical overlap with sclerotic fibroma (sclerotic pleomorphic fibroma). 2 Interestingly, independent of the stromal alteration, some cases of pleomorphic fibroma may have cytologically bland, mature adipocytes within the dermal compartment.…”

Slow-Growing Nodule in a Patient With Li-Fraumeni Syndrome: Answer

“…Pleomorphic fibroma was first described in 1989 by Kamino et al 1 It is a rare benign cutaneous tumor, typically presenting as solitary, small (<2 cm), pedunculated, or dome-shaped, and most frequently reported in middle-aged adults without a specific anatomic predilection. 2 Pleomorphic fibroma is believed to be of fibrohistiocytic cellular origin and is notable for its striking cytologic atypia in contrast to its indolent clinical presentation. 3 Classically, the lesion demonstrates loosely arranged spindle cells with marked nuclear pleomorphism within a sclerotic to myxoid stroma; mitotic activity is low.…”