Merkel Cell Carcinoma

This one was, as one playa confirmed, very hard.  This was one of my patients at Wilford Hall, and he had, as described, a rapidly growing painless nodule with a slight pinkness to it.  It was, as you see, fairly close to skin colored, as have been roughly half of the Merkels I have run across, and it had the consistency of a firm cyst, but it was not rock hard.  The differential was pretty straightforward:  metastatic disease versus Merkel Cell Carcinoma.  The path was consistent with "trabecular cell tumor" and as a result I gave the dermatopathologist a hard time for speaking in paleodermatologic terms.  

Your clues (use all available clues!!) were the patient's age, the location (an admittedly soft call), the history of rapid growth, the appearance of the lesion itself as above, but most importantly, you should have honed in on the fact that an incisional biopsy was performed, and it was a big incision.  Why would we do that???  Because we wanted a lot of tumor with which to work, in case it was a weird met.  It wasn't.

Papular Sarcoidosis

Sarcoidosis is a systemic granulomatous disease of unknown etiology which involves botht he skin and other internal organs, including lungs, lymph nodes, myocardium and CNS.

Interestingly, in Europe, the disease is primarily found in rural areas particularly in Scandinavia, and inthe US it happens to be more concentrated in African Americans than the general population.  The lesions are primarily papular, but can be verrucous, erythematous, psoriasiform and alopetic.

The lesions are usually asymptomatic, and concentrated over the head and neck, as well as the upper trunk.  The ddx would include benign adnexal tumors, disseminated deep fungal infection in immunocompromised individuals, or xanthelasma.    The clues in this individual are the papules that are clustered around the eyes and nose, as well as the race.

Acrodermatitis Chronica Atrophicans

ACA is a European form of borreliosis, caused by B. afzelii and B. garinii.  It is transmitted by the Ixodes ricinus tick, and causes a morphea-like eruption.  How do we treat it?  One point. It differs from Erythema Chronicum Migrans by its lack of a raised, borrelia-infested erythematous border and by its scar-like appearance.  Had I been confronted by this picture, without any history, I would have said morphea.  

European borreliosis is much less likely to have multiple lesions, versus US borreliosis, and arthritis i s common as a sequela in the US, unusual in Europe.  Also associated with B afzelii and garinii are lymphocytoma cutis, atrophoderma of Pasini and Pierini, and lichen sclerosus et atrophicus.  

Dermatomyositis

Although any of the collagen vascular diseases can cause periungual telangiectases (the plural of telangiectasia is telangiectases, not telangiectasias) the classic association is with dermatomyositis, since DM is almost universally associated with those findings, as opposed to scleroderma, SLE, and the other CVDs.  I did, however, give credit for any of the CVDs.  

The most common of the lab tests to be positive for DM is creatine phosphokinase (CPK) but aldolase, Jo-1, ANA or any one of a number of lab tests can be considered to be extremely common with DM.  Name three autoantibodies associated with DM for three points.  Also, abnormal EMGs would be considered an abnormal lab test, as would an abnormal muscle biopsy.

The classic skin findings for DM (other than periungual telaingiectases) are heliotrope rash (swelling and violaceous changes of the upper lids) and Gottron's papules.  Also, photosensitivity, urticarial changes, alopecia, fingertip ulceration, Raynaud's Phenomenon, hyperpigmentation and calcification may occur.

Splinter Hemorrhages

Splinter hemorrhages can be caused by a variety of conditions, and to name a few we have SBE, Acute BE, small vessel vasculitis, trichinosis (my favorite, but then again I love parasitology), small vessel disease due to collagen vascular disease, trauma (the most common reason- by far- for splinter hemorrhages), and antophospholipid antibodies.  This is an excellent example of splinter hemorrhages, and happens to be due to subacute bacterial endocarditis, although I would have bet trauma if I had to throw down a wager.

Septic Embolus

Bacterial endocarditis can manifest itself in many different ways:  neurologic focal changes due to embolic strokes, evidence of acute heart failure (Jugular Venous Distention, dependent edema, etc.) and, of course, those signs that are near and dear to our hearts, the cutaneous and pericutaneous manifestations.  

Think of it this way:  The infected valve (usually the mitral) has vegetations which are peeled off from time to time by the turbulent flow across the valve, and the emboli float around until they ball-valve into a narrow vessel.  That's where we see them. So, you can have petechiae, such as the conjunctival petechia above, or it can play out as splinter hemorrhages in the nails (note: SBE is not the only way one can get splinter hemorrhages), Osler's nodes (tender digital nodules), Janeway Lesions (nontender palmoplantar nodules) and Roth Spots (retinal hemorrhages).  

The reason for this subtle example is because you, as incredibly astute diagnosticians, won't know it if you haven't seen it.  Remember: we, along with the ophthalmologists, are the detectives in medicine.  When everyone else fails, they come to us.

Mycobacterium marinum infection

Well, since I asked for the classic story to go with such a presentation, I hoped most of you would hone in on the appearance, location and classic nature of the lesion.  This is violaceous, on the dorsal hand, multicentric (which implies infection) and does not involve the entire dorsal hand, which shoots down PCT and its imitators.  In my experience, pyoderma gangrenosum is more deep purple, is ulcerated and necrotic.  

So, what's the classic story?  She was cleaning her fish tank, (or working on her boat or scraping barnacles off her dock, etc. ) and got an abrasion; didn't think anything of it and a few weeks later she got these nodules on her hand.  

Now, what's THIS lady's story?  She doesn't remember anything at all.  No trauma, no fish tank, no barnacles.  But, she grew M. marinum, so who knows? Trust your eyes, not your ears!