We read with interest the study by Schmitt et al., which compared dermatopathology with NOS2/CCL27-based PCR for differentiating eczema from psoriasis.1 As biologic therapies increasingly depend on precise inflammatory endotyping, improving diagnostic discrimination between these two entities has become a clinically important priority. In this context, the reported molecular advantage is noteworthy, but several interpretive issues warrant clarification before routine implementation. First, this design does not invalidate the comparison, but it may have tended to overestimate the apparent diagnostic accuracy of histopathological classification. The reported molecular advantage should therefore be interpreted within a composite clinicopathological reference framework rather than against a fully external standard.2 Second, the reported advantage of PCR in ‘ambiguous cases’ is clinically relevant, but its interpretation should be more precise.3 Because these cases were defined by low dermatopathologist concordance rather than by prespecified indicators of clinicobiological difficulty, the subgroup is best understood as representing lesions with particularly high diagnostic ambiguity within an already biopsy-selected population. The findings therefore support PCR most directly as an adjunct in biopsy-selected cases, especially those with high ambiguity, rather than as evidence of broader superiority across difficult inflammatory dermatoses.4 A more clinically translatable framework would define reflex testing prospectively by features that precede marked diagnostic uncertainty, including site-specific atypia, treatment-altered histology or clinicopathological discordance. Third, the present study should primarily be read as evidence of improved diagnostic performance and reproducibility, rather than as a direct test of downstream clinical utility.5 This distinction does not diminish the value of the work, but clarifies the next evidentiary step. Prospective studies are now needed to determine whether predefined PCR use in biopsy-selected cases changes treatment assignment or accelerates correct classification in routine care. Schmitt et al. should be credited for moving molecular dermatodiagnostics closer to clinical relevance. At present, however, the evidence supports adjunctive promise rather than routine adoption. In the biologic era, the benchmark for diagnostic innovation is not improved classification alone, but whether it refines therapeutic choice, reduces avoidable misallocation of targeted treatments and warrants incorporation into reproducible care pathways. This work was supported by the National Natural Science Foundation of China (Grant No. 82203056). The authors report no relationships relevant to the contents of this paper to disclose. Not applicable. This manuscript is a scholarly commentary and does not involve human participants, human data, animal experiments or identifiable personal information. Data sharing not applicable to this article as no datasets were generated or analysed during the current study.
Sun et al. (Sat,) studied this question.