What is the biological basis of pattern formation of skin lesions?

Pattern recognition is at the heart of clinical dermatology and dermatopathology. Yet, while every practitioner of the art of dermatological diagnosis recognizes the supreme value of diagnostic cues provided by defined patterns of 'efflorescences', few contemplate on the biological basis of pattern formation in and of skin lesions. Vice versa, developmental and theoretical biologists, who would be best prepared to study skin lesion patterns, are lamentably slow to discover this field as a uniquely instructive testing ground for probing theoretical concepts on pattern generation in the human system. As a result, we have at best scraped the surface of understanding the biological basis of pattern formation of skin lesions, and widely open questions dominate over definitive answer. As a symmetry-breaking force, pattern formation represents one of the most fundamental principles that nature enlists for system organization. Thus, the peculiar and often characteristic arrangements that skin lesions display provide a unique opportunity to reflect upon--and to experimentally dissect--the powerful organizing principles at the crossroads of developmental, skin and theoretical biology, genetics, and clinical dermatology that underlie these--increasingly less enigmatic--phenomena. The current 'Controversies' feature offers a range of different perspectives on how pattern formation of skin lesions can be approached. With this, we hope to encourage more systematic interdisciplinary research efforts geared at unraveling the many unsolved, yet utterly fascinating mysteries of dermatological pattern formation. In short: never a dull pattern!

The smell of burnt toast: a case report.

A 71-year-old woman awoke one morning to find that she perceived all aromas, odors, and fragrances as smelling like burnt toast. Over the next three years, numerous studies and therapeutic trials failed to elicit the cause of her dysosmia or to provide relief. Finally, the demonstration of small infarcts as seen on a brain MRI suggested that an infarct near the olfactory pathway was responsible for the sudden onset and the 11 year persistence of her unique paromia.

The drug line: the clinical expression of the pigmentary Voigt-Futcher line in turn derived from the embryonic ventral axial line.

BACKGROUND: Observation of patients with morbilliform eruptions reveals a distinctive demarcation line on the upper arms. OBJECTIVE: We studied the origin of this sharp "drug line." METHODS: We performed a literature search of all known variables. RESULTS: The drug line represents clinical expression of the pigmentary Voigt-Futcher line. CONCLUSION: The drug line reveals the otherwise inapparent embryologic ventral axial line, which marks the precise border between the sensory innervation of the lateral and medial upper arm. The significance of the cutaneous sensory nerves is thus apparent. The drug line is further evidence of the segmental nature of human skin, as evidenced in evolutionary and embryologic studies.

Chronic factitial ulcer of chin cured by endodontic (root-canal) surgery for underlying periapical abscess.

In a determined search for the cause of a "factitial" ulcer of the jaw, consultation with 3 dentists was required before an underlying periapical abscess was discovered. Within 3 months of endodontic surgery, this ulcer of 12 years duration had completely healed and remains healed. Too often dental infection is neither suspected nor detected as a cause of skin disease.

Long-term antibiotic therapy for balanitis xerotica obliterans.

In an open uncontrolled study of 3 patients with balanitis xerotica obliterans we have observed significant improvement after long-term systemic antibiotic therapy. Two of the patients noticed softening of the skin as well as disappearance of pruritus, tenderness, and inflammatory changes within 3 weeks of receiving oral and intramuscular penicillin. The third patient experienced the same degree of improvement after a regimen of dirithromycin, 500 mg/day. Stopping the antiobiotic for 1 month resulted in relapse, with improvement again on resumption.

Chronic staphylococcal scalded skin syndrome.

Staphylococcal scalded skin syndrome (SSSS), not previously recorded as a chronic disease, persisted for 2 years in a 50-year-old woman with epilepsy and cerebellar ataxia. Lesions initially suggestive of erythema multiforme and toxic epidermal necrolysis evolved over 2 years into those typical for SSSS, with extensive erosions and subcorneal blisters, showing an epidermal split at the granular cell layer. Exfoliatin A-producing phage I-III Staphylococcus aureus, previously linked only to acute mild adult cases of SSSS, was cultured from purulent discharge in the patient's eyes, ears and open skin lesions. The roles of epilepsy and antiepileptic medications are discussed as possible predisposing factors.

Botulinum toxin therapy for palmar hyperhidrosis.

BACKGROUND: Severe palmar hyperhidrosis is a chronic disease, resistant to conventional therapy. Botulinum toxin inhibits sweat production by blocking release of acetylcholine from presynaptic membranes. OBJECTIVE: Our purpose was to evaluate the short- and long-term effectiveness of botulinum toxin therapy in treatment of palmar hyperhidrosis. METHODS: Four patients with severe palmar hyperhidrosis were treated with subepidermal injections of botulinum toxin. Fifty injections, 2 mouse units each, were used in each palm. Regional nerve blocks of the median and ulnar nerves were performed before the procedure. Patients were observed for 12 months after treatment. RESULTS: Botulinum toxin injections significantly reduced sweat production in the treated areas of the palms. Anhidrosis lasted for 12 months in one patient, 7 months in two patients, and 4 months in one patient. Mild weakness of the thumb lasting 3 weeks occurred in one patient. No other side effects were observed. CONCLUSION: Botulinum toxin provides an effective, safe, and long-lasting alternative therapeutic modality for treatment of severe palmar hyperhidrosis. Additional studies are needed for optimization of the technique.

Aquadynia: noradrenergic pain induced by bathing and responsive to clonidine.

We describe two women in whom bathing was regularly followed by intense, widespread burning pain that lasted 15 to 45 minutes, which we term aquadynia. This water-induced pain was not caused by any skin or systemic diseases. We view it as a type of noradrenergic pain induced by contact with water, because it can be blocked with clonidine or propranolol. It appears to be an extension of the phenomenon of aquagenic pruritus, which we have also found to respond to clonidine or propranolol.