This study has confirmed the potential of TPI to identify the extent of BCC in vivo and to delineate tumour margins. Further clinical study of TPI as a surgical tool is now required.

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WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Very little is known about the physiology of P‐glycoprotein (P‐gp) expression in the lungs. • Ex vivo evidence based on resected lung tissue suggests that pulmonary P‐gp is upregulated by cigarette smoke, but there are no in vivo studies to date. WHAT THIS STUDY ADDS • The novel observation that healthy cigarette smokers have a delayed pulmonary elimination rate of inhaled 99mTc‐sestamibi, a P‐gp substrate, provides for the first time a potential method for quantifying functional pulmonary P‐gp expression that may inform about drug therapy by inhalation as well as provide a non‐invasive, quantitative, human biomarker for assessing P‐gp modulators. AIM To explore inhaled technetium‐99m‐labelled hexakis‐methoxy‐isobutyl isonitrile (99mTc‐sestamibi) for quantifying pulmonary P‐glycoprotein (P‐gp) expression. METHODS The elimination rate from the lungs of 99mTc‐sestamibi was recorded scintigraphically for 30 min following inhalation as an aerosol in healthy smokers, nonsmokers and patients with lung disease. RESULTS 99mTc‐sestamibi elimination rates [% min−1 (SD; P vs. healthy nonsmokers)] were: healthy nonsmokers, 0.43 (0.083); healthy smokers, 0.19 (0.056; P < 0.001); chronic obstructive pulmonary disease patients, 0.26 (0.077; P < 0.001). Elimination rates in three patients with interstitial lung disease were not accelerated. CONCLUSION Cigarette smoke upregulates lung P‐gp. 99mTc‐sestamibi elimination in normal smokers could be used to test new P‐gp modulators. The findings also have implications for inhaled drug delivery.

References1 Silverberg NB, Herz J, Wagner A, Paller AS. Erythema dyschromicum perstans in prepubertal children. Pediatr Dermatol 2003; 20: 398-403. 2 Ing EB, Buncic JR, Weiser BA, de Nanassy J, Boxall L. Periorbital hyperpigmentation and erythema dyschromicum perstans. Can J Ophthalmol 1992; 27: 353 -355. 3 Ramirez CO. The ashy dermatosis (erythema dyschromicum perstans) -epidemiological study and report of 139 cases. Cutis 1967; 3: 244 -247. 4 Knox JM, Dodge BG, Freeman RG. Erythema dyschromicum perstans. Arch Dermatol 1968; 97: 262 -272. 5 Novick NL, Phelps R, Tom C. Erythema dyschromicum perstans. Int J Dermatol 1986; 25: 322 -323. 6 Sanchez NP, Pathak MA, Sato SS et al. Circumscribed dermal melaninoses: classification, light, histochemical, and electron microscopic studies on three patients with the erythema dyschromicum perstans type. Int J Dermatol 1982; 21: 25-31. 7 Gross A, Tapia FJ, Mosca W et al. Mononuclear cell subpopulation and infiltrating lymphocytes in erythema dyschromicum perstans and vitiligo. Histol Histopathol 1987; 2: 277 -283. 8 Mizukawa Y, Shiohara T. Fixed drug eruption presenting as erythema dyschromicum perstans: a flare without taking any medications. Dermatology 1998; 197: 383 -385. 9 Kontochristopoulos G, Stavropoulos P, Panteleos D, Aroni K. Erythema dyschromicum perstans: response to dapsone therapy. Int J Dermatol 1998; 37: 796 -798. 10 Baranda L, Torres-Alvarez B, Cortes-Franco R et al.Involvement of cell adhesion and activation molecules in the pathogenesis of erythema dyschromicum perstans (ashy dermatitis). The effect of clofazimine therapy.

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Pyoderma gangrenosum (PG) is an idiopathic inflammatory disease of unknown aetiology, frequently associated with an underlying systemic condition such as inflammatory bowel disease or haematological malignancy. Its occurrence tends to parallel exacerbations of the underlying disease. Four clinical variants of PG have been described and these include ulcerative, pustular, bullous and vegetative types. We report two cases of the pustular form, which is an uncommon variant of PG, where the pustules do not progress to form ulcers. Both our patients suffered with inflammatory bowel disease which remained quiescent as the pustular PG developed.

Although the role of P-gp expression in the clearance of 99mTc-sestamibi remains unproven, we conclude that 99mTc-tetrofosmin is not as P-gp-avid as 99mTc-sestamibi. A role for P-gp expression in the clearance of 99mTc-sestamibi remains unproven. Higher doses of P-gp inhibitors will be required and clearance rates correlated with immunohistochemical expression of P-gp.

Keratoacanthoma centrifugum marginatum (KCM) is a rare variant of keratoacanthoma (KA), characterised by a progressively expanding tumour with a lack of spontaneous remission and significant scarring. KCM has been reported previously in less than 50 cases worldwide. We present the case of a large solitary KCM on the right shin of a 71-year-old woman. This was treated successfully with oral acitretin for 16 months with sustained remission at 24 months. Our case provides further supporting evidence for acitretin as a useful treatment for KCM to induce remission, prevent extensive surgery and minimise destructive scarring.