Pseudoporphyria

Pseudoporphyria is a blistering eruption,usually of the dorsal hands, which is triggered by an exogenous medication.  The most commonly implicated of the meds are the NSAIDs, although a whole host of others have been implicated- even aspirin!

The presentation is a blistering eruption on the dorsal hands, and the ddx is EBA, PCT and PseudoPCT.  Careful history will rule out PCT, and if there is a history of NSAID use in combination with sun exposure, you've got your culprit.

Ten days into April, we've got a three way tie for first, with a bunch of you one point behind.  Keep it up!

Penile Scabies

There are lots of different diseases which can pop up on the penis, many of which can be obscure as far as the dx.  Psoriasis, lichen planus, Zoon's balanitis, candida, Lichen sclerosus et atrophicus, allergic contact dermatitis, herpes, all the nasty STDs (chancres, chancroid, etc.) and scabies; but precious few of them itch.  In fact, as a predominant symptom, Pso, LP, Zoon's, Candida, HSV, Chancroid and often LS&A burn or hurt as a presenting symptom.  ACD and scabies: they itch. As a primary symptom, scabies particularly will drive the patients crazy.  As one of our playas said:  "Itchy red papules on the penis are scabies until proven otherwise."  'Nuff said.  Same playa pointed out his favorite spot to look for eggs or mites is underneath the fingernails.  That's a nifty trick for all of you from Redding, California.  Nice job, Brian.

Digital Mucous Cyst

Digital Mucous Cysts are really outpouchings of the synovial joint space of the distal interphalangeal joint.  They are incredibly common in the older age groups, are almost always associated with DIPJ osteoarthritis, and are, of course, benign. They often cause a groove or depression in the nail plate as a result of pressure on the nail matrix, and they are usually asymptomatic.  They are largely of cosmetic consequence only.  At MIMA, if they require treatment, we send them to a hand surgeon.

Many of you picked a synonym for DMCs, and they are allowed.  Happy weekend, Happy Passover and Happy Easter, everyone!

Positive KOH

KOH exams are one of the fundamental skills we are must possess to be good at taking care of peoples's skin.  The trick to a good KOH exam is to get adequate scale, ensure the patient has not had antifungals prior to the exam, preparing the slide properly and knowing what a positive exam looks like.  

When scraping for a KOH, get far more scale than you think youneed.  Try to get it from inflamed and noninflamed areas, and after scrpaing the scale onto the lside, drop the KOH solution (we use Swarz-Lamkins) onto the slide, and then lightly heat the slide until the small bubbles underneath the cover slip expand, but before the fluid boils.

After slide prep, expect the slide to be readable: no thick scale on the slide, good stain, all the carbon suet removed from the slide.  Examine the slide by using a quick up and down motion of the objective, it will help you identify which are real hyphal elements and which are just cell borders.

This slide is very positive, as demonstrated by the parallel margins of the cell walls of the hyphal elements, the septations and the branches coming off the main hyphae.

Microcystic Adnexal Carcinoma

Rather than belabor the relationship between infiltrative BCCs and MACs, I will instead list what is the reasonable differential diagnosis.  I did not count off for wrong answers, but did give credit for right ones. Here's the DDx as accepted by most dermatologists:  Scar, MAC, Infiltrative BCC, Desmoplastic trichoepithelioma, post-LN2 hypopigmentation (although I've never seen it look like this) and vitiligo (never seen it look like this, either.  For those of you who put regressed MM, I will grant that, although it is entirely atypical for that, but I did not give credit for amelanotic MM, because they are pink or red. I really want to make the point that any scar that is irregular or round on the face demands an explanation, and if no history of trauma exists, then biopsy is indicated.  

No infectious causes would be this discrete, and except as above, no inflammatory processes would be, either.

Infiltrative Basal Cell Carcinoma

Infiltrative basal cell carcinomas are tough.  They can be small or overwhelmingly large, and often clinical examination doesn't tell just how big they are.  They are best thought of as worm holes down into the dermis, and they look like our image when cut en face for viewing under the microscope.  Normal basal cells have large balls of tumor (which look like little beads when we biopsy them) and usually are surrounded by mucin (which explains why they are sticky and want to adhere to our razor blade or scalpel when we shave biopsy them). 

Think of nodular basal cells as cauliflower.  When you thin slice cauliflower, the slice looks like individual balls of material, but in actuality they were attached to the main stalk of the cauliflower.  Infiltrative basal cells, on the other hand, extend as worm holes down into the tissue, and the way to think of them in 3-D is as if you were thin slicing a mass of cold spaghetti.  if you looked at only the thin slice, it would look almost exactly like this slide: some of the strands would be viewed straight on, others are cut at an angle so as to give the appearance of little spikes and strands of tissue.  

Why bother with this?  Because once you get the "zen" of this tumor, you will be able to understand how to defeat it.  The best way, by far, is by Mohs surgery.  We can track down all the individual strands and tentacles that extend form the main body of the tumor, and that will give you the highest cure rate.  But, you say, I don't do Mohs!  Well, you can either take a wide margin around what you see as the edge of the tumor, or you can use a little trick:  Stretch the skin, and look for blanching,  Since the tumor is a space-occupying lesion in the dermis, it displaces blood vessels and so when you stretch the skin around the tumor, it blanches out the skin where the tumor is.  That is a more accurate way of predicting the margin.  Many of you are doing surgeries, and when you are approaching basals and SCCs it is helpful to define the margins as well as you can.  Along with stretching the skin, also consider curetting the tissue prior to excision for nodular BCCs and SCCs.  It'll cut way down on your positive margin rate.  On infiltratives, that won't work because the strands of tumor are too small for the curette to be able to adequately define.  

The clinical differential diagnoses for these infiltrative tumors are scars, microcystic adnexal carcinomas, a benign growth known as a desmoplastic trichoepithelioma, and the occasional weird large syringoma.  If the infiltrative tumor has increased collagen under the microscope, it is known as "sclerosing", which means "scarring". 

Small clinical tumors can be very large:

Infiltrative BCC post-Mohs

One final point:  nodular basals can be triggered into becoming infiltrative with external trauma, such as consistent scratching, or from partial treatment, especially by using liquid nitrogen on nodular and superficial BCCs.  It is imperative that you biopsy what you don't know, and only freeze those lesions that you KNOW are actinic keratoses.

The Treasury Petra, Jordan

Petra is one of the most amazing places in the world.  It was the center of the Nabatean Kingdom, and was, amazingly, unknown to the outside world until 1812.  The Nabateans were traders whose caravansary worked the area from the Dead Sea down to present day Yemen, at the southern tip of the Arabian Peninsula.  Their power came from these trade routes, which started out from oasis to oasis, but then evolved to a complex network of man-made oases, where cisterns were dug into the rock and thus the annual rains would collect in these cisterns, and then the caravans would use them as watering stations for their camels.  In a way, they made the desert their fortress, because without the knowledge of where these watering holes were, the invaders and bandits were out of luck. They, and they alone, could get the goods from one spot in the desert to another.  They were FedEx before FedEx was FedEx.

Petra was carved from the sandstone of the Jordanian desert in the 300 B.C. era, and was remarkably unnoticeable from the surrounding countryside.  It really amounts to a canyon, with its own water supply (controlled by a sophisticated aqueduct system) and inhospitable surroundings which made invaders more reluctant to pick a fight.  Out of this sandstone canyon were carved spectacular buildings, most of which had Greek-inspired architecture, and the most spectacular of these is The Treasury, which is, as one of our playas pointed out, known as Al Khazneh in Arabic.  There are lots of yarns about why it was called the Treasury, but I'm pretty sure the real reason why is that the Swiss archeologist who discovered it probably labelled it according to his own sensibilities. (Hey, he was Swiss; the Swiss really, really love their banks, and so you see where I'm going with this...)

One of the Indiana Jones movies was shot there, as another playa pointed out, and the area outside the actual historical site is replete with Indiana Jones souvenir shops.  You can take camel rides, but the rides are sort of like the pony rides we used to take as a kid, with the actual Jordanian camel driver leading your camel past all the historic sites, before they drop you off at their cousin's souvenir shop.  They are pushy, but in a roguish, fun sort of way.  Their kids can work a crowd for money better than Barack Obama, and the mothers usually sit in the shadows, scowling at the western women who are immodestly dressed.  Culture meets commerce.  

Of course, the dromedary camel is the ship of the desert, and although they have a face only a mother could love, they are pretty cool.  They take their time going where they are going, grumble loudly if prodded, and act up for no apparent reason.  Instead of calling them the ships of the desert, it's more like "teenagers of the desert".  

Well, my brain has had a break, so it's back to derm mañana, but many of you hoovered up two points on an interesting little side trip on our road to knowledge.