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MNJ14-001
A 13-year-old girl Reema comes to your hospital with complaints of acute onset painful swelling below her knee joint down to the ankle. She recently visited a school camp for 3 days where she shared a room with her batchmates. On examination, you find painful erythematous nodular lesions over the shins, and her pharynx is erythematous:

  1. What is the most likely diagnosis of these lesions?
  2. What are the infectious causes of these lesions (list 4)?
  3. Which drugs can be responsible for these?

Answer

  1. Diagnosis: Erythema nodosum (septal panniculitis).
  2. Infectious causes:
    • Streptococcal pharyngitis (Group A Streptococcus - most common)
    • Tuberculosis (Mycobacterium tuberculosis)
    • Mycoplasma pneumoniae
    • Salmonella / Yersinia enterocolitica
    • Epstein-Barr virus (EBV) / Coccidioidomycosis / Histoplasmosis
  3. Drugs: Sulfonamides, penicillins, oral contraceptive pills (OCPs), NSAIDs, bromides/iodides.

MNJ14-002
MNJ-P-OSCE 14. Dermatology_page_6_Picture_1.jpeg
MNJ-P-OSCE 14. Dermatology_page_6_Picture_2.jpeg

See the images of 2 neonates (Image A and Image B) and answer the following questions:

  1. What is the diagnosis of Image A and Image B?
  2. How long do these persist in a normal neonate?
  3. In which subgroup of gestational age are these two more commonly seen?
  4. What are the treatment options for Image A and Image B?

Answer

  1. Diagnosis:
    • Image A: Erythema toxicum neonatorum (ETN).
    • Image B: Neonatal cephalic pustulosis / Acne neonatorum.
  2. Duration / Course:
    • Image A (Erythema toxicum): Appears at 24–48 hours of life and resolves spontaneously within 7–10 days.
    • Image B (Acne neonatorum): Appears around 2–3 weeks of life and may persist for several weeks up to 6–8 months.
  3. Gestation: Both are significantly more common in full-term, healthy newborns (rare in premature infants).
  4. Treatment:
    • Image A: Reassurance and gentle skin care; no treatment required.
    • Image B: Usually self-limiting; gentle cleansing with water. If severe/persistent, topical 2% ketoconazole cream or mild topical hydrocortisone.

MNJ14-003
MNJ-P-OSCE 14. Dermatology_page_6_Picture_9.jpeg

See the image and answer the following questions:

  1. What is the clinical finding in this picture?
  2. What is the embryological pathophysiology for this?
  3. What are the differential diagnoses (list 2)?
  4. What is its natural course in a child?
  5. What other organ system should you screen/examine if you find this in a neonate?

Answer

  1. Finding: Preauricular skin tag (accessory tragus).
  2. Pathophysiology: Defective or abnormal fusion of the first and second branchial arches (specifically the hillocks of His) during embryogenesis.
  3. Differential diagnosis: Epidermal inclusion cyst, preauricular fibroma, adnexal tumor, lipoma, neurofibroma.
  4. Course: Benign and asymptomatic; persists lifelong unless surgically excised.
  5. Other system: Renal system (routine screening / USG KUB if associated with other dysmorphic features or hearing impairment; screen for Goldenhar syndrome, BOR syndrome, Treacher Collins syndrome).

MNJ14-004
MNJ-P-OSCE 14. Dermatology_page_7_Picture_1.jpeg

A 6-year-old child comes to you with fever and cough. During chest examination, you notice an unusual finding along the chest wall:

  1. What is the clinical finding in this picture?
  2. What is the milk line?
  3. What is its male-to-female ratio and recommended management?

Answer

  1. Finding: Polythelia / Accessory (supernumerary) nipple.
  2. Milk line (mammary ridge): An imaginary embryological line extending bilaterally from the anterior axillary fold down to the inguinal region along which mammary glands develop in mammals.
  3. Demographics & Management:
    • Equal frequency in males and females (1:1).
    • Management: Reassurance; benign anomaly requiring no treatment. Surgical excision may be performed for cosmetic reasons or recurrent irritation.

MNJ14-005
MNJ-P-OSCE 14. Dermatology_page_7_Picture_9.jpeg

  1. What is the diagnosis shown in this newborn?
  2. What are the common causes/triggers in a neonate?
  3. What is the pathophysiology for this finding?
  4. What is the clinical course?
  5. What is the treatment?
  6. What electrolyte should you monitor in this case and what complication can develop?

Answer

  1. Diagnosis: Subcutaneous fat necrosis of the newborn (SCFN).
  2. Causes / Predisposing factors: Perinatal asphyxia, hypothermia/therapeutic hypothermia, birth trauma, maternal gestational diabetes, pre-eclampsia, meconium aspiration.
  3. Pathophysiology: Neonatal subcutaneous fat contains a high concentration of saturated fatty acids (stearic and palmitic acids) with a high melting point. Cold injury or tissue hypoperfusion induces fat crystallization within adipocytes, leading to necrosis, giant cell reaction, and granulomatous panniculitis.
  4. Course: Lesions evolve over weeks to months from firm, red-purple indurated plaques/nodules to soft, fluctuant areas with spontaneous resolution.
  5. Treatment: Supportive care and watchful monitoring; lesions resolve spontaneously without active treatment.
  6. Electrolyte monitoring & Complication:
    • Serum Calcium: Monitor bi-weekly for up to 6 months.
    • Complication: Severe hypercalcemia (due to extra-renal production of 1,25-dihydroxyvitamin D by activated macrophages in granulomas), which can lead to nephrocalcinosis, cardiac arrhythmias, and failure to thrive.

MNJ14-006
MNJ-P-OSCE 14. Dermatology_page_8_Picture_1.jpeg

A 13-year-old child Rajeev with known atopic dermatitis comes to your clinic with these new itchy lesions that began in December and increased in size over a month. He is on regular emollients and has not traveled recently:

  1. What is the diagnosis of this condition?
  2. What are the differential diagnoses?
  3. How will you manage these lesions?

Answer

  1. Diagnosis: Nummular eczema (discoid eczema).
  2. Differential diagnosis:
    • Tinea corporis (fungal infection)
    • Contact dermatitis
    • Plaque psoriasis
    • Pityriasis rosea (herald patch)
  3. Management:
    • Gentle, soap-free cleansers and warm (not hot) baths.
    • Frequent application of thick bland emollients/moisturizers (petrolatum/ceramide creams).
    • Mid- to high-potency topical corticosteroids applied to active lesions.
    • Topical calcineurin inhibitors (tacrolimus/pimecrolimus) for maintenance.
    • Oral antihistamines for pruritus control.

MNJ14-007
MNJ-P-OSCE 14. Dermatology_page_8_Picture_6.jpeg

These 2 patients presented with cutaneous lesions: Patient A is hospitalized and had adhesive tape applied across his abdomen; Patient B wears a tight metallic belt buckle regularly:

  1. What is the diagnosis in both images? Do they represent the same underlying problem?
  2. Which type of allergic hypersensitivity reaction is this?
  3. What treatment can you offer for these patients?

Answer

  1. Diagnosis: Allergic contact dermatitis (Patient A due to adhesive acrylate/tape; Patient B due to nickel/metal buckle). Yes, both represent allergic contact dermatitis.
  2. Immunologic reaction: Type IV (delayed-type / cell-mediated) hypersensitivity reaction.
  3. Treatment:
    • Strict avoidance/removal of the offending allergen (hypoallergenic paper tape; nickel-free belt buckle or barrier cloth).
    • Application of topical corticosteroids (hydrocortisone or betamethasone).
    • Calamine lotion / cool compresses and oral antihistamines for symptomatic itch relief.

MNJ14-008
MNJ-P-OSCE 14. Dermatology_page_9_Picture_1.jpeg

A 7-day-old neonate comes with complaints of recurrent blister and skin peel formation following minor friction, rubbing, or clothing contact:

  1. What is the most likely diagnosis?
  2. What is the recurrence risk in future pregnancies?
  3. What is the pathophysiology and genetic basis?
  4. What is the usual course and prognosis?

Answer

  1. Diagnosis: Epidermolysis bullosa (EB - simplex / junctional / dystrophic).
  2. Recurrence risk:
    • Autosomal Dominant (e.g., EB Simplex): 50% risk for each pregnancy.
    • Autosomal Recessive (e.g., Junctional or recessive Dystrophic EB): 25% risk per pregnancy.
  3. Pathophysiology & Genetics: Mutations in structural proteins that maintain epidermal-dermal integrity:
    • KRT5 / KRT14 on chromosomes 12q and 17q (EB simplex)
    • LAMA3, LAMB3, LAMC2, COL17A1 (Junctional EB)
    • COL7A1 on chromosome 3p (Dystrophic EB)
  4. Course: Fragility often persists throughout life; managed with non-adherent silicone dressings, skin protection, prevention of secondary infections, and nutritional support.

MNJ14-009
MNJ-P-OSCE 14. Dermatology_page_9_Picture_7.jpeg

A 4-month-old boy Rahul presents with itchy, grouped tense blisters over the extremities:

  1. What is the likely diagnosis?
  2. What is the characteristic pattern of these lesions called?
  3. What is found on direct immunofluorescence (DIF) / electron microscopy?
  4. What is the prognosis?

Answer

  1. Diagnosis: Linear IgA bullous dermatosis of childhood (Chronic bullous disease of childhood [CBDC]).
  2. Pattern: "String of pearls" or "Cluster of jewels" pattern (rosette-like arrangement of new tense vesicles around resolving crusted plaques).
  3. Immunofluorescence / EM finding: Continuous linear deposition of IgA along the basement membrane zone (subepidermal split with cleavage through lamina lucida).
  4. Prognosis: Excellent; usually a benign, self-limiting disorder that responds dramatically to oral Dapsone and resolves spontaneously within 2–4 years.

MNJ14-010
MNJ-P-OSCE 14. Dermatology_page_10_Picture_1.jpeg

A mother of a 13-year-old child presents for URI and shows an abnormal hyperpigmented lesion on her child's neck that has darkened and developed irregular surface changes:

  1. What is the likely diagnosis?
  2. What are 4 possible differential diagnoses?
  3. What advice will you give the mother regarding future observation?

Answer

  1. Diagnosis: Congenital melanocytic nevus (CMN) / Giant pigmented nevus.
  2. Differential diagnosis:
    • Mongolian spot (congenital dermal melanocytosis)
    • Nevus of Ota / Nevus of Ito
    • Blue nevus
    • Becker's nevus
    • Plexiform neurofibroma
  3. Advice / Follow-up:
    • Monitor for signs of malignant melanoma transformation using the ABCDE criteria:
      • A: Asymmetry
      • B: Border irregularity
      • C: Color variegation / darkening
      • D: Diameter >6 mm or rapid expansion
      • E: Evolution / Elevation / Ulceration / Bleeding
    • Regular clinical examination and prompt biopsy if any rapid changes occur.

MNJ14-011
MNJ-P-OSCE 14. Dermatology_page_10_Picture_6.jpeg

Mother of a 5-year-old girl comes for consultation regarding multiple brown macules on her back present since birth. The child also has poor growth, sensorineural hearing loss, and a congenital heart lesion on echocardiography:

  1. What are these skin lesions called?
  2. What is the associated genetic syndrome?
  3. What are the clinical components of this syndrome?

Answer

  1. Lesions: Multiple lentigines (scattered hyperpigmented macules).
  2. Syndrome: LEOPARD syndrome (Noonan syndrome with multiple lentigines; PTPN11 mutation).
  3. Mnemonic Components (LEOPARD):
    • L: Lentigines (multiple dark-brown macules)
    • E: ECG conduction abnormalities
    • O: Ocular hypertelorism
    • P: Pulmonary stenosis
    • A: Abnormalities of genitalia (hypogonadism, cryptorchidism)
    • R: Retardation of growth
    • D: Deafness (sensorineural hearing loss)

MNJ14-012
MNJ-P-OSCE 14. Dermatology_page_11_Picture_5.jpeg

A 24-hour-old neonate of a diabetic mother is in the NICU. On changing the diaper in a cool room, a lace-like reticular reddish-blue mottling is observed over the lower extremities:

  1. What is the likely diagnosis of this condition?
  2. What is the cause/pathophysiology?
  3. What is the prognosis?

Answer

  1. Diagnosis: Cutis marmorata (physiologic mottling).
  2. Cause / Pathophysiology: Normal physiological vasomotor response to cold ambient temperature, resulting from immature autonomic vascular regulation leading to alternating venular dilation and arteriolar constriction.
  3. Prognosis: Completely benign and transient; disappears upon re-warming and gradually resolves as the infant's autonomic vasomotor control matures over early infancy.

MNJ14-013
MNJ-P-OSCE 14. Dermatology_page_11_Picture_10.jpeg
MNJ-P-OSCE 14. Dermatology_page_12_Picture_1.jpeg

See the image of well-demarcated depigmented patches on the skin:

  1. What is the diagnosis of this lesion?
  2. What endocrine screening test will you order for this child?
  3. What are the primary treatment options?

Answer

  1. Diagnosis: Vitiligo (autoimmune melanocyte destruction).
  2. Endocrine test: Thyroid profile (Free T4, TSH, anti-TPO antibodies), as autoimmune thyroid disease (Hashimoto thyroiditis/Grave's) occurs in up to 20–30% of vitiligo patients.
  3. Treatment options:
    • Topical corticosteroids (mid-to-high potency) or topical calcineurin inhibitors (tacrolimus 0.03%–0.1%, pimecrolimus).
    • Phototherapy: Narrowband UVB (NB-UVB) or targeted excimer laser.
    • Systemic steroids (oral mini-pulse) for rapidly progressive disease.
    • Strict photoprotection with broad-spectrum sunscreens.

MNJ14-014
MNJ-P-OSCE 14. Dermatology_page_12_Picture_7.jpeg

A child presents with acute onset fever, respiratory distress, septic shock, and rapidly spreading ecchymoses and necrotic purpura. Blood tests show a deranged coagulation profile:

  1. What is the diagnosis of this condition?
  2. What are 4 possible etiologies?
  3. What are the expected results for D-dimer, fibrin degradation products (FDPs), and plasma fibrinogen?
  4. What is the emergency treatment for this child?

Answer

  1. Diagnosis: Purpura fulminans (Disseminated Intravascular Coagulation with microvascular skin necrosis).
  2. Etiologies:
    • Severe bacterial sepsis (Neisseria meningitidis / meningococcemia, Streptococcus pneumoniae, Staphylococcus aureus, Gram-negative rods)
    • Severe viral infections (varicella, measles)
    • Congenital or acquired Protein C / Protein S / Antithrombin III deficiency
    • Catastrophic antiphospholipid syndrome
  3. Lab results:
    • D-dimer & FDPs: Markedly elevated
    • Fibrinogen level: Significantly decreased (consumed)
    • (Prolonged PT/INR and aPTT, severe thrombocytopenia)
  4. Treatment:
    • Immediate aggressive resuscitation (airway, high-flow O2, IV fluid boluses, vasopressors).
    • Prompt broad-spectrum parenteral antibiotics (e.g., 3rd gen cephalosporin + vancomycin).
    • Blood product replacement: Fresh Frozen Plasma (FFP), cryoprecipitate (to replete fibrinogen), and platelet concentrates.
    • Protein C concentrate replacement if indicated.

MNJ14-015
MNJ-P-OSCE 14. Dermatology_page_12_Picture_12.jpeg

A 5-year-old boy Pankaj Gulati presents with a 1-week history of widespread pruritic and painful vesicular and bullous lesions arranged in an annular configuration with crusting:

  1. What is the diagnosis?
  2. What is the characteristic description of this lesion pattern?
  3. Which immunoglobulin deposition is classically identified on direct immunofluorescence (DIF)?

Answer

  1. Diagnosis: Linear IgA bullous dermatosis of childhood (Chronic bullous disease of childhood).
  2. Pattern: "String of pearls" or "Cluster of jewels" appearance (new tense vesicles ringing the periphery of resolving central lesions).
  3. Immunopathology: Continuous linear deposition of IgA along the basement membrane zone (BMZ) on direct immunofluorescence.