Spindle Cell–Predominant Trichodiscoma With a Palisaded Arrangement of Stromal Cells
Bibliographic record
Abstract
To the Editor: Spindle cell–predominant trichodiscoma is one of the histologic variants along the fibrofolliculoma–trichodiscoma hamartomatous spectrum.1 It features a central cellular stroma of spindled cells arranged in interweaving fascicles associated with prominent peripheral mitt-like sebaceous lobules.2 A variant of spindle cell–predominant trichodiscoma that demonstrated a focal palisaded arrangement of stromal cells reminiscent of schwannoma has been described.3 This variant is particularly interesting, given the historic classification of these lesions as neurofollicular hamartomas4–6 and its ability to resemble neural neoplasms. To the best of our knowledge, only one spindle cell–predominant trichodiscoma with a palisaded pattern has been presented in the English-language literature to date. Here, we present a second case, which featured a diffuse palisaded pattern. The lesion was excised from the nose of a 49-year-old woman. It was a solitary papule measuring 3 mm in diameter and was reported to have been present for 5 years, with an increase in size in the previous year. Clinically, it was thought to be either an intradermal nevus or a nodular basal cell carcinoma. Histologically, the lesion was a small circumscribed protuberant nodule located in the upper dermis and was composed primarily of haphazard fascicles of spindled stromal cells showing a prominent palisading pattern (Fig. 1). This striking palisaded pattern gave the lesion a neural-like appearance, quite reminiscent of schwannoma. There were some small vessels in the background and occasional lipocytes were also seen focally. Sebaceous lobules were present at the periphery of the central mesenchymal component, in a pattern that is in keeping with trichodiscoma.FIGURE 1.: Spindle cell–predominant trichodiscoma showing a prominent palisaded arrangement of stromal cells (A and B). Note the peripherally situated sebaceous lobules typical of trichodiscoma (A).Immunohistochemical stains revealed the stromal cells to be strongly and diffusely positive for CD34 and completely negative for S100 (Fig. 2). CD31 mainly highlighted background small vessels, with only quite minimal granular staining in stromal cells. There was also minimal patchy staining with CD10. Factor XIIIa highlighted scattered dendritic cells. Neurofilament, epithelial membrane antigen , smooth muscle actin, muscle-specific actin, desmin, h-caldesmon, collagen type IV, and MART-1 were negative. A Ki67 stain demonstrated a very low proliferative index.FIGURE 2.: The stromal cells are strongly and diffusely positive for CD34 (A) and are negative for S100 (B).This second reported case of a spindle cell–predominant trichodiscoma with a palisaded arrangement of stromal cells further demonstrates the degree of palisading that may be present within these lesions. As mentioned by Kacerovska et al,3 despite the resemblance the stromal component may have to schwannoma, the characteristic epithelial component is helpful in recognizing these lesions as trichodiscomas. Immunohistochemistry confirms the diagnosis.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.003 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".