Three new cases of follicular mucinosis have been described. In addition to the characteristic changes in hair follicles and sebaceous glands, all three cases showed mucinous degeneration of the dermis. In one case the staining reactions with PAS and Giemsa stains appeared to indicate that the dermal mucin differed from the follicular mucin, and contained a glycoprotein rather than acid mucopolysaccharides. Because of the high percentage of spontaneous regression, it is difficult to evaluate the response to therapy. Rapid response of one case to systemic corticosteroids suggested that this therapy had an actual effect.
—The article by Weiss et al1does not present convincing evidence that application of topical tretinoin improves photoaged skin, even within the context of the small number of patients studied and the short follow-up period. Photographic factors must be kept constant for valid demonstration of subtle morphological changes in "before" and "after" pictures. The presentation in this article does not meet this requirement. Examination of the published clinical photographs (Figs 1 through 3 in the article by Weiss et al) reveals a significant and consistent increase in photographic contrast in the "after" pictures (apparently due mainly to lighting, with a possible development factor). This results in "washing out" of the highlighted areas and a darkening of the shadow areas, with consequent loss of photographic detail, which could easily account for the apparent diminution of fine wrinkling and pigmented spots after treatment with tretinoin. The disappearance of
The differential diagnosis of melanocytic lesions is fraught with difficulty and a common source of litigation either if a lesion misreported as 'benign' recurs locally or re-presents with nodal metastases or if an atypical naevus is called 'malignant' leading to a cosmetically unsatisfactory wider resection, unwarranted anxiety about prognosis and adverse life insurance prospects. Several authors have claimed that there are valid morphological criteria which, alone or in combination, enable reliable distinction between benign and malignant melanocytic lesions. Others question these criteria and, doubting the extent to which unequivocal diagnoses can be rendered in all cases, believe that the diagnosis is purely subjective and that most diagnostic errors are non-negligent. To address these issues, expert opinions were commissioned from three sets of authors. Okun, Edelstein & Kasznica emphasize that a significant minority of melanocytic lesions are so borderline morphologically that diagnostic uncertainty is allowable and that such uncertainty can be handled responsibly. Kirkham, in favouring the methodical use of criteria, concedes that they are 'largely opinion-based rather than evidence-based, but do go beyond mere subjective pattern analysis'. In agreement with Okun and his colleagues. Slater emphasises that no single feature is reliable by itself and that all aspects, including clinical details, should be interpreted together; he has no hesitation in reporting the diagnosis as 'uncertain' in doubtful cases. In the absence of a specific marker pathognomonic of melanocytic malignancy, the diagnosis will continue to rely on the judicious application of morphological criteria with a small proportion of elusive cases in which diagnostic uncertainty should not be concealed.
Evidence of new cell formation from nucleoli (subdivisional cell replication) was observed in vitro and in vivo. Mouse melanoma cells, human fibroblasts, and rat mast cells were observed in tissue culture with phase contrast time-lapse cinematography. Evidence of subdivisional cell replication seen in tissue culture was supported by observations of mast cells, cervical epithelial cells, melanoma cells, keratinocytes, and fungal spores in vivo. Indirect evidence for subdivisional cell replication was the presence of differentiated form and function in nuclei and nucleoli. Synergism between subdivisional replication and mitotic replication (subdivisional expansion) is believed to be a key to morphogenesis, whereby cellular and subdivisional zones act as biologic "molds". It is believed that subdivisional cell replication has a key role in maintenance of differentiated form in multicellular organisms, as well as in morphogenesis.
